mmc: core: generalize hw reset functionality for all cards

MMC_CAP_HW_RESET capability was only referring to host driver
capability to toggle eMMC RST_n pin so if the host driver is
unable to toggle this pin, it shouldn't advertise this capability
and in that case, we should exercise power cycling of the eMMC
card to reset it.

CRs-Fixed: 507926
Change-Id: Ia2c6ad5f5bb22cc0cd8cf3bd09835eda73c7a444
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>