mmc: replace CONFIG_GENERIC_MMC with CONFIG_MMC

Now CONFIG_GENERIC_MMC and CONFIG_MMC match for all defconfig.
We do not need two options for the same feature.  Deprecate the
former.

This commit was generated with the sed script 's/GENERIC_MMC/MMC/'
and manual fixup of drivers/mmc/Kconfig.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/board/hisilicon/hikey/hikey.c b/board/hisilicon/hikey/hikey.c
index 0f0eb3a..47bce4d 100644
--- a/board/hisilicon/hikey/hikey.c
+++ b/board/hisilicon/hikey/hikey.c
@@ -341,7 +341,7 @@
 	return 0;
 }
 
-#ifdef CONFIG_GENERIC_MMC
+#ifdef CONFIG_MMC
 
 static int init_dwmmc(void)
 {