mmc: core: add missing pm event in mmc_pm_notify to fix hib restore

mmc: core: add missing pm event in mmc_pm_notify to fix hib restore

The PM_RESTORE_PREPARE is not handled now in mmc_pm_notify(),
as result mmc_rescan() could be scheduled and executed at
late hibernation restore stages when MMC device is suspended
already - which, in turn, will lead to system crash on TI dra7-evm board:

WARNING: CPU: 0 PID: 3188 at drivers/bus/omap_l3_noc.c:148 l3_interrupt_handler+0x258/0x374()
44000000.ocp:L3 Custom Error: MASTER MPU TARGET L4_PER1_P3 (Idle): Data Access in User mode during Functional access

Hence, add missed PM_RESTORE_PREPARE PM event in mmc_pm_notify().

Fixes: 4c2ef25fe0b8 (mmc: fix all hangs related to mmc/sd card...)
Signed-off-by: Grygorii Strashko <Grygorii.Strashko@linaro.org>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>