mmc: rtsx: Remove redundant suspend and resume callbacks

Suspend and resume of cards are handled by the protocol layer and
consequently the mmc_suspend|resume_host APIs are marked as deprecated.

While moving away from using the deprecated APIs, there are nothing
left to be done for the suspend and resume callbacks, so remove them.

Cc: Wei WANG <wei_wang@realsil.com.cn>
Cc: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Chris Ball <cjb@laptop.org>