mmc: rename CONFIG_ROCKCHIP_DWMMC to CONFIG_MMC_DW_ROCKCHIP

mmc: rename CONFIG_ROCKCHIP_DWMMC to CONFIG_MMC_DW_ROCKCHIP

I am trying to make all DesignWare-based driver options prefixed
with CONFIG_MMC_DW_.

This commit was generated as follows:

find . -name .git -prune -o -type f -print | \
xargs sed -i -e 's/ROCKCHIP_DWMMC/MMC_DW_ROCKCHIP/g'

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Marek Vasut <marex@denx.de>