MLK-22851-1 mmc: fsl_esdhc: reduce unnecessary clock change

In mmc initial state, the mmc framework sets clock to 0, so the fsl_esdhc
driver converts to use min clock 400Khz. But the priv->clock is logged
400Khz not 0, and cause following calls to set_ios to set clock again.

Each set to clock has 10ms delay for stable, then the problem accumulates
some unnecessary delay.

Signed-off-by: Ye Li <ye.li@nxp.com>
(cherry picked from commit 151ab3bef2b1ec1c142c31048f3005ebce2a7a18)