msm: kgsl: Remove ADRENO_DEVICE_HARD_RESET flag

Current hang recovery sequence does not try soft reset
for all GMU enabled targets. ADRENO_DEVICE_HARD_RESET
flags is indication to go for hard reset sequence incase
soft reset fails. The latest a6xx_reset() sequence will
not to do any soft reset for GMU enabled targets. Hence
remove the ADRENO_DEVICE_HARD_RESET flag which does
not have any significance.

Change-Id: I44f492545f68d0555780a4c9cb49e24e1e582bc6
Signed-off-by: Hareesh Gundu <hareeshg@codeaurora.org>