clk: meson: g12a: add missing SD_EMMC_A controller gates

Add missing SD_EMMC_A controller gates needed for probe of the A
controller, otherwise leading to a freeze of the SoC after b3d69aa5.

Fixes: b3d69aa5 ("clk: meson: reset mmc clock on probe")
Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>