ENGR00174905 [MX6] gc355 can't work after specific suspend/resume case

ENGR00174905 [MX6] gc355 can't work after specific suspend/resume case

GC355 can't work at below steps:
- suspend resume
- load gpu driver and run gc355 application

In order to make GPU work properly, GPU clock needs to be on while power
on GPU. Not only direct GPU clk ccgr needs to be on, but also relative
clock in GPU clock tree has to be enabled.

Signed-off-by: Larry Li <b20787@freescale.com>