msm: kgsl: Fix an overrun while constructing the GPMU load command

The calculation for the size of the buffer to contain the load
commands for the GPMU firmware was off - the size was calculated
using the type4 max size (128) but that includes the opcode, so
it really should have been the payload size (127).

Change-Id: Ic0dedbad1920c94c72ee38bfcd62ce0ac60efeb2
Signed-off-by: Jordan Crouse <jcrouse@codeaurora.org>