mmc: via-sdmmc: Move away from using deprecated APIs

Suspend and resume of cards are being handled from the protocol layer
and consequently the mmc_suspend|resume_host APIs are deprecated.

This means we can simplify the suspend|resume callbacks by removing the
use of the deprecated APIs.

Cc: Bruce Chang <brucechang@via.com.tw>
Cc: Harald Welte <HaraldWelte@viatech.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>