clk: msm: gcc: Add efuse based fmax for GPU clk for MSM8940

MSM8940 requires to support the maximum frequency of 500MHz for
GPU clock, so add support to read the efuse register and update the
list of supported frequencies and fmax tables accordingly.

Change-Id: I7b76a666663455413bab39c598a05a5d0b5feb51
Signed-off-by: Odelu Kukatla <okukatla@codeaurora.org>