MdeModulePkg/SdMmcPciHcDxe: Fix bus timing switch sequence

MdeModulePkg/SdMmcPciHcDxe: Fix bus timing switch sequence

REF: https://bugzilla.tianocore.org/show_bug.cgi?id=2218

SD specification recommends switching card bus timing before
switching bus timing in controller. Emmc driver used to do
this switch other way around. This commit adds controller
timing switch in EmmcSwitchBusTiming function to enforce this
order and removes all controller timing programming from
EmmcSwitchToXXX functions.

Signed-off-by: Mateusz Albecki <mateusz.albecki@intel.com>
Reviewed-by: Hao A Wu <hao.a.wu@intel.com>
Tested-by: Hao A Wu <hao.a.wu@intel.com>
Tested-by: Marcin Wojtas <mw@semihalf.com>