pinctrl: add polarfire soc mssio pinctrl driver

On Polarfire SoC, the Bank 2 and Bank 4 IOs connected to the
Multiprocessor Subsystem (MSS) are controlled by IOMUX_CRs 1 through 6,
which determine what function in routed to them, and
MSSIO_BANK#_IO_CFG_CRs, which determine the configuration of each pin.

Add a driver for this pin controller, including several custom
properties that reflect aspects of the MSS's configuration.

Reuse the Kconfig option for iomux0, since controlling MSSIOs without
iomux0 routing a function to the MSSIOs in question is pointless, and
routing a function to the MSSIOs is equally unhelpful if none of them
are configured to make use of that function.

Signed-off-by: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Linus Walleij <linusw@kernel.org>

drivers/pinctrl/microchip/Kconfig

@@ -9,9 +9,9 @@ config PINCTRL_PIC64GX
 	  This selects the pinctrl driver for gpio2 on pic64gx.
 
 config PINCTRL_POLARFIRE_SOC
-	bool "Polarfire SoC pinctrl driver"
+	bool "Polarfire SoC pinctrl drivers"
 	depends on ARCH_MICROCHIP || COMPILE_TEST
 	depends on OF
-	select GENERIC_PINCONF
+	select GENERIC_PINCTRL
 	help
-	  This selects the pinctrl driver for Microchip Polarfire SoC.
+	  This selects the pinctrl drivers for Microchip Polarfire SoC.

drivers/pinctrl/microchip/Makefile

@@ -2,3 +2,4 @@
 
 obj-$(CONFIG_PINCTRL_PIC64GX)	+= pinctrl-pic64gx-gpio2.o
 obj-$(CONFIG_PINCTRL_POLARFIRE_SOC)	+= pinctrl-mpfs-iomux0.o
+obj-$(CONFIG_PINCTRL_POLARFIRE_SOC)	+= pinctrl-mpfs-mssio.o