mmc: sdhci: Fix MMC HS200 tuning command failures

This patch fixes the mmc tuning command failures
when tuning pattern data needs to read back for
comparision against the expected bit pattern.

Reported-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Siva Durga Prasad Paladugu <siva.durga.paladugu@xilinx.com>
Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Tested-by: Masahiro Yamada <yamada.masahiro@socionext.com>