mmc: sdhci: Remove redundant condition

The logic '!mmc.f_max || (mmc.f_max && mmc.f_max > max_clk)'
is equivalent to '!mmc.f_max || mmc.f_max > max_clk'.

Reported-by: David Binderman <dcb314@hotmail.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>