mmc: complete unfinished move of CONFIG_MMC

Commit 7a777f6d6f35 ("mmc: Add generic Kconfig option") created
a Kconfig entry for this option without any actual moves, then
commit 44c798799f66 ("sunxi: Use Kconfig CONFIG_MMC") moved
instances only for SUNXI.

We generally do not like such partial moves.  This kind of work
is automated by tools/moveconfig.py, so it is pretty easy to
complete this move.

I am adding "default ARM || PPC || SANDBOX" (suggested by Tom).
This shortens the configs and will ease new board porting.

This commit was created as follows:

[1] Edit Kconfig (remove the "depends on", add the "default",
    copy the prompt and help message from Linux)

[2] Run 'tools/moveconfig.py -y -s -r HEAD MMC'

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
diff --git a/configs/axs101_defconfig b/configs/axs101_defconfig
index b8d8baf..04f5ffe 100644
--- a/configs/axs101_defconfig
+++ b/configs/axs101_defconfig
@@ -1,6 +1,7 @@
 CONFIG_ARC=y
 CONFIG_SYS_DCACHE_OFF=y
 CONFIG_SYS_CLK_FREQ=750000000
+CONFIG_MMC=y
 CONFIG_SYS_TEXT_BASE=0x81000000
 CONFIG_DEFAULT_DEVICE_TREE="axs10x"
 CONFIG_BOOTDELAY=3