[KCONFIG] add SYS_EARLY_PCI_INIT to Kconfig

CONFIG_SYS_EARLY_PCI_INIT is referenced in board_r.c, but it's not defined
in any Kconfig. Add it to drivers/pci/Kconfig

drivers/pci/Kconfig

@@ -26,6 +26,14 @@ config DM_PCI_COMPAT
 	  measure when porting a board to use driver model for PCI. Once the
 	  board is fully supported, this option should be disabled.
 
+config SYS_EARLY_PCI_INIT
+	bool "Enable early initialization for PCI"
+	depends on PCI
+	default n
+	help
+	  Do early PCI configuration _before_ the flash, sysdata and MMC get
+	  initialised.
+
 config PCI_AARDVARK
 	bool "Enable Aardvark PCIe driver"
 	default n