mmc: davinci_mmc: Handle error for clk_enable

As the potential failure of the clk_enable(),
it should be better to check it and return error
if fails.

Fixes: bbce5802 ("davinci: mmc: updates to suspend/resume implementation")
Signed-off-by: Jiasheng Jiang <jiasheng@iscas.ac.cn>
Link: https://lore.kernel.org/r/20220308071415.1093393-1-jiasheng@iscas.ac.cn


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