mmc: core: remove needless err = 0 in mmc_init_card()

Since they will always being in successful path to return 0 directly,
no need to set err = 0.

Signed-off-by: Yue Hu <huyue2@yulong.com>
Link: https://lore.kernel.org/r/20210113113431.522-1-zbestahu@gmail.com


Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>