mfd: Remove STA2x11 core driver

With commit dcbb01f ("x86/pci: Remove old STA2x11 support"), the core
driver for STA2x11 is not needed and cannot be built anymore.

Remove the driver and its header file.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20250303100055.372689-1-lukas.bulwahn@redhat.com
Signed-off-by: Lee Jones <lee@kernel.org>

Author: bulwahn

drivers/mfd/Kconfig

@@ -1508,12 +1508,6 @@ config STMPE_SPI
 	  This is used to enable SPI interface of STMPE
 endmenu
 
-config MFD_STA2X11
-	bool "STMicroelectronics STA2X11"
-	depends on STA2X11
-	select MFD_CORE
-	select REGMAP_MMIO
-
 config MFD_SUN6I_PRCM
 	bool "Allwinner A31/A23/A33 PRCM controller"
 	depends on ARCH_SUNXI || COMPILE_TEST

drivers/mfd/Makefile

@@ -26,7 +26,6 @@ obj-$(CONFIG_MFD_TI_LP873X)	+= lp873x.o
 obj-$(CONFIG_MFD_TI_LP87565)	+= lp87565.o
 obj-$(CONFIG_MFD_TI_AM335X_TSCADC)	+= ti_am335x_tscadc.o
 
-obj-$(CONFIG_MFD_STA2X11)	+= sta2x11-mfd.o
 obj-$(CONFIG_MFD_STMPE)		+= stmpe.o
 obj-$(CONFIG_STMPE_I2C)		+= stmpe-i2c.o
 obj-$(CONFIG_STMPE_SPI)		+= stmpe-spi.o