drm/i915/psr: Fix register name mess up.

Commit 77affa31 ("drm/i915/psr: Fix compiler warnings for
hsw_psr_disable()") swapped status and control registers while fixing
indentation. The _ctl at the end of the status register name must have to
led to this.

Fixes: 77affa31

 ("drm/i915/psr: Fix compiler warnings for hsw_psr_disable()")
References: https://www.mrc-cbu.cam.ac.uk/people/matt.davis/cmabridge/
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Dhinakaran Pandiyan <dhinakaran.pandiyan@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171220043520.2599-1-dhinakaran.pandiyan@intel.com
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>