mmc: wmt-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: Tony Prisk <linux@prisktech.co.nz>
Cc: linux-arm-kernel@lists.infradead.org
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>