spi: meson: Select REGMAP_MMIO

The Meson SPIFC driver uses regmap mmio functions and so it must
select REGMAP_MMIO to avoid the following build error:

spi-meson-spifc.c: undefined reference to `devm_regmap_init_mmio_clk'
Reported-by: Jim Davis <jim.epost@gmail.com>
Signed-off-by: Beniamino Galvani <b.galvani@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/Kconfig

@@ -304,6 +304,7 @@ config SPI_FSL_ESPI
 config SPI_MESON_SPIFC
 	tristate "Amlogic Meson SPIFC controller"
 	depends on ARCH_MESON || COMPILE_TEST
+	select REGMAP_MMIO
 	help
 	  This enables master mode support for the SPIFC (SPI flash
 	  controller) available in Amlogic Meson SoCs.