uboot-imx

rockchip: remove SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR from defconfig

Use default value 0x4000 for SYS_MMCSD_RAW_MODE_U_BOOT_SECTOR instead
of define a new one.

Signed-off-by: Kever Yang <kever.yang@rock-chips.com>
Acked-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>
Reviewed-by: Philipp Tomsich <philipp.tomsich@theobroma-systems.com>