mmc: sdhci-msm: fix issue with SD card tuning functionality

The commit 'e2598c - mmc: sdhci-msm: improve tuning process'
introduces NULL pointer dereference bug for SD 3.0 cards
when all the tuning phases pass. It uses mmc_card_mmc(card)
for checking the card type but card is initialized after
tuning is done for SD card and thus resulting in NULL
pointer dereference issue.

CRs-fixed: 640424
Change-Id: I59a8d5f017243d8391269bc98998bb37fc44f685
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>