ARM: sunxi: Fix build break when CONFIG_MMC is not defined
BOOT_TARGET_DEVICES includes MMC unconditionally. This breaks when
CONFIG_CMD_MMC is not defined. Use a secondary macro to conditionally
include it when CONFIG_MMC is enabled, as we do for CONFIG_AHCI.
This is used when we want to use uart0 from port F, which conflicts
with mmc0.
Signed-off-by: Chen-Yu Tsai <wens@csie.org> Acked-by: Ian Campbell <ijc@hellion.org.uk>