mmc: sdhci: fix compilation issue when PM configs are not defined

Fix the following compilation issue when CONFIG_PM_SLEEP is defined and
CONFIG_PM_RUNTIME is not defined -

error: implicit declaration of function 'sdhci_msm_runtime_suspend'
[-Werror=implicit-function-declaration]
return sdhci_msm_runtime_suspend(dev);
^
error: implicit declaration of function 'sdhci_msm_runtime_resume'
[-Werror=implicit-function-declaration]
return sdhci_msm_runtime_resume(dev);
^
cc1: some warnings being treated as errors
make[5]: *** [drivers/mmc/host/sdhci-msm.o] Error 1

Change-Id: Id720f595746888c81c07426aab0c850cbaeccf0c
Signed-off-by: Sahitya Tummala <stummala@codeaurora.org>