mmc: sh_mmcif: use sh_mmcif_xxx prefix for all functions

Current sh_mmcif driver is using sh_mmcif_xxx and mmcif_xxx
for functions. This patch used sh_mmcif_xxx for all functions.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Tested-by: Keita Kobayashi <keita.kobayashi.ym@renesas.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>