The PCI bus notifier is only visible if CONFIG_PCI symbol is selected in
Kconfig. But this driver can be built without CONFIG_PCI due to
CONFIG_COMPILE_TEST, leading to below build error:

   drivers/power/sequencing/pwrseq-pcie-m2.c: In function 'pwrseq_pcie_m2_free_resources':
>> drivers/power/sequencing/pwrseq-pcie-m2.c:185:34: error: 'pci_bus_type' undeclared (first use in this function); did you mean 'pci_pcie_type'?
     185 |         bus_unregister_notifier(&pci_bus_type, &ctx->nb);
         |                                  ^~~~~~~~~~~~
         |                                  pci_pcie_type
   drivers/power/sequencing/pwrseq-pcie-m2.c:185:34: note: each undeclared identifier is reported only once for each function it appears in
   drivers/power/sequencing/pwrseq-pcie-m2.c: In function 'pwrseq_pcie_m2_register_notifier':
   drivers/power/sequencing/pwrseq-pcie-m2.c:340:54: error: 'pci_bus_type' undeclared (first use in this function); did you mean 'pci_pcie_type'?
     340 |                         ret = bus_register_notifier(&pci_bus_type, &ctx->nb);
         |                                                      ^~~~~~~~~~~~
         |                                                      pci_pcie_type

So add guards to make sure that all these helper functions making use of
the PCI bus notifier are only compiled if CONFIG_PCI is selected.

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603180609.ucspJefN-lkp@intel.com
Fixes: 3f736aecbdc8 ("power: sequencing: pcie-m2: Create serdev device for WCN7850 bluetooth")
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@oss.qualcomm.com>
---
 drivers/power/sequencing/pwrseq-pcie-m2.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/power/sequencing/pwrseq-pcie-m2.c b/drivers/power/sequencing/pwrseq-pcie-m2.c
index a75ca4fda2eb..d3102fea8d93 100644
--- a/drivers/power/sequencing/pwrseq-pcie-m2.c
+++ b/drivers/power/sequencing/pwrseq-pcie-m2.c
@@ -177,6 +177,7 @@ static int pwrseq_pcie_m2_match(struct pwrseq_device *pwrseq,
 	return PWRSEQ_NO_MATCH;
 }
 
+#if IS_ENABLED(CONFIG_PCI)
 static int pwrseq_m2_pcie_create_bt_node(struct pwrseq_pcie_m2_ctx *ctx,
 					struct device_node *parent)
 {
@@ -374,6 +375,12 @@ static int pwrseq_pcie_m2_register_notifier(struct pwrseq_pcie_m2_ctx *ctx, stru
 
 	return 0;
 }
+#else
+static int pwrseq_pcie_m2_register_notifier(struct pwrseq_pcie_m2_ctx *ctx, struct device *dev)
+{
+	return 0;
+}
+#endif /* CONFIG_PCI */
 
 static int pwrseq_pcie_m2_probe(struct platform_device *pdev)
 {
@@ -452,8 +459,10 @@ static void pwrseq_pcie_m2_remove(struct platform_device *pdev)
 {
 	struct pwrseq_pcie_m2_ctx *ctx = platform_get_drvdata(pdev);
 
+#if IS_ENABLED(CONFIG_PCI)
 	bus_unregister_notifier(&pci_bus_type, &ctx->nb);
 	pwrseq_pcie_m2_remove_serdev(ctx);
+#endif
 
 	regulator_bulk_free(ctx->num_vregs, ctx->regs);
 }
-- 
2.51.0