sunxi: bpi-m3: Enable eMMC

Add CONFIG_MMC_SUNXI_SLOT_EXTRA=2 to use eMMC on
BPI_M3 board.

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Tested-by: Jagan Teki <jagan@amarulasolutions.com>

configs/Sinovoip_BPI_M3_defconfig

@@ -12,6 +12,7 @@ CONFIG_USB0_ID_DET="PH11"
 CONFIG_USB1_VBUS_PIN="PD24"
 CONFIG_AXP_GPIO=y
 CONFIG_SATAPWR="PD25"
+CONFIG_MMC_SUNXI_SLOT_EXTRA=2
 CONFIG_DEFAULT_DEVICE_TREE="sun8i-a83t-sinovoip-bpi-m3"
 # CONFIG_SYS_MALLOC_CLEAR_ON_INIT is not set
 CONFIG_CONSOLE_MUX=y