MMC S5P: Fix typo

Fix typo resulting in the compilation error

s5p_mmc.c: In function 's5p_mmc_initialize':
s5p_mmc.c:469: error: 'struct mmc' has no member named 'm_bmax'

introduced by commit "MMC: make b_max unconditional"
(8feafcc4)

Signed-off-by: Dirk Behme <dirk.behme@googlemail.com>
CC: John Rigby <john.rigby@linaro.org>
CC: Andy Fleming <afleming@freescale.com>
Signed-off-by: Minkyu Kang <mk7.kang@samsung.com>