ARM: tegra: clock: Add function to set SDMMC tap delay

The SDMMC controllers have extra bits in the clock source
register that adjust the delay between the clock and data
to compenstate for delays on the PCB.  The values need to
be set from the clock code so the clock can be locked
during the read-modify-write on the clock source register.

Acked-by: Olof Johansson <olof@lixom.net>
Signed-off-by: Colin Cross <ccross@android.com>