spi: mediatek: add spi slave for Mediatek MT2712

This patch adds basic spi slave for MT2712.

Signed-off-by: Leilk Liu <leilk.liu@mediatek.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
diff --git a/drivers/spi/Makefile b/drivers/spi/Makefile
index 1920b6c..644b22e 100644
--- a/drivers/spi/Makefile
+++ b/drivers/spi/Makefile
@@ -88,6 +88,7 @@
 obj-$(CONFIG_SPI_SH_MSIOF)		+= spi-sh-msiof.o
 obj-$(CONFIG_SPI_SH_SCI)		+= spi-sh-sci.o
 obj-$(CONFIG_SPI_SIRF)		+= spi-sirf.o
+obj-$(CONFIG_SPI_SLAVE_MT27XX)          += spi-slave-mt27xx.o
 obj-$(CONFIG_SPI_SPRD)			+= spi-sprd.o
 obj-$(CONFIG_SPI_SPRD_ADI)		+= spi-sprd-adi.o
 obj-$(CONFIG_SPI_STM32) 		+= spi-stm32.o