drivers: pcie: initialize after interrupt controllers

PCIe devices refer to interrupt nodes, but are initialized with the same
priority, making the sequence depending on the linking order. Add a new
symbol and set it to one unit after intc to ensure that the
initialization sequence is stable.

Found with:

west build -p -b qemu_cortex_a53 \
	samples/drivers/virtualization/ivshmem/doorbell \
	-DCONFIG_CHECK_INIT_PRIORITIES=y
...
ERROR: /soc/pcie@4010000000 PRE_KERNEL_1 40 <
	/soc/interrupt-controller@8000000/its@8080000 POST_KERNEL 40

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>

drivers/pcie/host/Kconfig

@@ -14,6 +14,12 @@ module = PCIE
 module-str = pcie
 source "subsys/logging/Kconfig.template.log_config"
 
+config PCIE_INIT_PRIORITY
+	int "PCIe initialization priority"
+	default 41
+	help
+	  PCIe host drivers initialization priority.
+
 config PCIE_CONTROLLER
 	bool "PCIe Controller management"
 	help

drivers/pcie/host/pcie.c

@@ -554,4 +554,4 @@ static int pcie_init(void)
 #define PCIE_SYS_INIT_LEVEL	PRE_KERNEL_1
 #endif
 
-SYS_INIT(pcie_init, PCIE_SYS_INIT_LEVEL, CONFIG_KERNEL_INIT_PRIORITY_DEFAULT);
+SYS_INIT(pcie_init, PCIE_SYS_INIT_LEVEL, CONFIG_PCIE_INIT_PRIORITY);

drivers/pcie/host/pcie_ecam.c

@@ -403,7 +403,7 @@ static const struct pcie_ctrl_driver_api pcie_ecam_api = {
 			      &pcie_ecam_data##n,				\
 			      &pcie_ecam_config##n,				\
 			      PRE_KERNEL_1,					\
-			      CONFIG_KERNEL_INIT_PRIORITY_DEFAULT,		\
+			      CONFIG_PCIE_INIT_PRIORITY,			\
 			      &pcie_ecam_api);
 
 DT_INST_FOREACH_STATUS_OKAY(PCIE_ECAM_INIT)