mmc: core: Select HS mode in device first and then in the host

While switching from hs400 to hs200 mode, high speed mode
timing should be selected in the device before changing the
clock frequency in the host. But current implementation,
(mmc_hs400_to_hs200) first updates the frequency in the host
and then updates mode in the device. This is a spec violation.
Hence update the sequence to comply with the spec.

Change-Id: I0694edac9dd005ec68add9cc38bbe6fa4245ed48
Signed-off-by: Sayali Lokhande <sayalil@codeaurora.org>