Fix MMC access on Sabrelite

It appears that MMC access on the Sabrelite has been broken since
cdcaee9518:

Loading Environment from MMC... Card did not respond to voltage select!
*** Warning - No block device, using default environment

Remove the board_mmc_init() and related entries now that we should be
using DM_MMC, add PINCTRL so that things work as expected.

Signed-off-by: Martyn Welch <martyn.welch@collabora.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Troy Kisky <troy.kisky@boundarydevices.com>
Acked-by: Troy Kisky <troy.kisky@boundarydevices.com>
diff --git a/configs/mx6qsabrelite_defconfig b/configs/mx6qsabrelite_defconfig
index ea338c1..39b0ef7 100644
--- a/configs/mx6qsabrelite_defconfig
+++ b/configs/mx6qsabrelite_defconfig
@@ -28,6 +28,7 @@
 # CONFIG_RANDOM_UUID is not set
 CONFIG_CMD_I2C=y
 CONFIG_CMD_MMC=y
+# CONFIG_CMD_PINMUX is not set
 CONFIG_CMD_SATA=y
 CONFIG_CMD_USB=y
 CONFIG_CMD_USB_MASS_STORAGE=y
@@ -55,6 +56,8 @@
 CONFIG_PHY_MICREL=y
 CONFIG_PHY_MICREL_KSZ90X1=y
 CONFIG_MII=y
+CONFIG_PINCTRL=y
+CONFIG_PINCTRL_IMX6=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_MXC_SPI=y