Convert CONFIG_HSMMC2_8BIT to Kconfig

This converts the following to Kconfig:
   CONFIG_HSMMC2_8BIT

Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/configs/am335x_shc_defconfig b/configs/am335x_shc_defconfig
index 9d81f8d..5a6db3c 100644
--- a/configs/am335x_shc_defconfig
+++ b/configs/am335x_shc_defconfig
@@ -72,6 +72,7 @@
 CONFIG_SYS_I2C_SLAVE=0x1
 CONFIG_SYS_I2C_SPEED=400000
 CONFIG_MMC_OMAP_HS=y
+CONFIG_HSMMC2_8BIT=y
 CONFIG_PHY_ADDR_ENABLE=y
 CONFIG_PHY_SMSC=y
 CONFIG_MII=y