msm: kgsl: Combine MSG_START HFI and gmu quirk

The gmu quirk serves well to identify targets that use
legacy firmware. MSG_START HFI happens to be supported
only in non-legacy firmware. So use the quirk to figure
out whether to send the MSG_START HFI or not.

Change-Id: I711ceae53104e6be1d456589d582439a6a8c68f9
Signed-off-by: Harshdeep Dhatt <hdhatt@codeaurora.org>