mmc: ftsdc010: Drop non-dm code

Only three defconfig(adp-ag101p_defconfig,
adp-ae3xx_defconfig, nx25-ae250_defconfig)
set CONFIG_FTSDC010=y. And they all also
enable CONFIG_DM_MMC. So the non-dm code
of ftsdc010 can be dropped now.

Signed-off-by: Rick Chen <rick@andestech.com>
Signed-off-by: Rick Chen <rickchen36@gmail.com>
Cc: Greentime Hu <green.hu@gmail.com>