mmc: msm_sdcc: Clean up clock management and add a 10us delay after enabling clocks

It appears that in some cases there may be a delay on the ARM9 in enabling our clock.
As a result, we may put the controller into a bad state. Delay 10us after enabling
clocks to let the peripheral settle. Note - this is all imperical.

Also ensure set_ios() callback grabs the host lock.

Signed-off-by: San Mehat <san@google.com>
Signed-off-by: Daniel Walker <dwalker@codeaurora.org>