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>
diff --git a/configs/popmetal-rk3288_defconfig b/configs/popmetal-rk3288_defconfig
index 663724e..5a4e1b8 100644
--- a/configs/popmetal-rk3288_defconfig
+++ b/configs/popmetal-rk3288_defconfig
@@ -42,7 +42,7 @@
 CONFIG_SPL_CLK=y
 CONFIG_ROCKCHIP_GPIO=y
 CONFIG_SYS_I2C_ROCKCHIP=y
-CONFIG_ROCKCHIP_DWMMC=y
+CONFIG_MMC_DW_ROCKCHIP=y
 CONFIG_PINCTRL=y
 CONFIG_SPL_PINCTRL=y
 # CONFIG_SPL_PINCTRL_FULL is not set