gpu: pvr: no need to check for retry failures in SGXTestActivePowerEvent

gpu: pvr: no need to check for retry failures in SGXTestActivePowerEvent

Powering off can't fail now with a 'retry' error, so we can't have the
corresponding condition here. See the similar commits earlier in the
patchset for a more detailed explanation.

Signed-off-by: Imre Deak <imre.deak@nokia.com>
CC: Mark Underwood <mark.underwood@imgtec.com>
CC: Mark Riding <mark.riding@imgtec.com>
Reviewed-by: Topi Pohjolainen <topi.pohjolainen@nokia.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@nokia.com>