msm: kgsl: Make kgsl_pwrctrl_axi return a value

On gmu targets, we may fail the boot bandwidth hfi, so
return the error all the way up.

Change-Id: I059fb18090ae6cb33af3c0b53f2a8fd5875b7e52
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>