msm: clock: Use CLKFLAG_NO_RATE_CACHE in clk_set_parent

Some use cases involve the rate of a parent changing
from under a child. Therefore the set_parent op needs
a chance to update the rate field. Use the
CLKFLAG_NO_RATE_CACHE to allow the clk_set_parent to
go through to the set_parent op.

Change-Id: Icaf48915322539c84ef522621e35dafebe08b23b
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>