msm: dcvs: set gpu actual freq when setting gpu floor

If actual_freq of gpu is not updated when a gpu floor
is set, TZ is unaware of the gpu frequency change and
computations are based on an incorrect value. By setting
actual_freq, TZ is notified of the new gpu frequency at
the next idle exit.

Change-Id: Ifc69996ef309ed4f8a5d46a2048757e57dd1a8ec
Signed-off-by: Steve Muckle <smuckle@codeaurora.org>