msm: acpuclock-8226: Increase freq used during PLL switching

While changing the rate of the main pll, the pll must be off. During this
time, the cpu runs off of an alternative source. Change the rate of the
alternative source used from 19.2 MHz to 300 MHz.

Change-Id: I0b6b6c655f4d66a8e3d24ae2628916f09ea71989
Signed-off-by: Patrick Daly <pdaly@codeaurora.org>