GC600: Fix bug that cause to crash when doing hibernate Driver tries to enable...

GC600: Fix bug that cause to crash when doing hibernate Driver tries to enable clock gating during GPU hardware initialization. CPU needs to stall a little time to wait for GPU ready

BugLink: http://bugs.launchpad.net/bugs/611634

Signed-off-by: Saeed Bishara <saeed@marvell.com>
Signed-off-by: Eric Miao <eric.miao@canonical.com>
Signed-off-by: Brad Figg <brad.figg@canonical.com>