mmc: tmio: sdhi: Track SMPCMP valu in private data

Retain the SMPCMP value from last calibration in private data.
This will be later used for skipping bad taps.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>