clk: qcom: clock-mmss-8992: Update venus clock frequencies

The vcodec0_clk_src now supports 320 MHz instead of 266.67 MHz
as the nominal clock frequency, according to the latest frequency
plan. Update the same in the clock driver.

Change-Id: I4af9668c2efd6b815d827f168af7d787c7ee36ed
Signed-off-by: Pushkar Joshi <pushkarj@codeaurora.org>