Nokia RX-51: Convert to CONFIG_DM_MMC

Move twl4030_power_mmc_init() from board_mmc_power_init() to misc_init_r()
and disable CONFIG_SYS_MALLOC_F. Otherwise U-Boot cannot initialize MMC.
Also disable CONFIG_CMD_SLEEP CONFIG_DM_DEVICE_REMOVE CONFIG_MMC_VERBOSE to
free some space.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Tom Rini <trini@konsulko.com>