drm/i915: slightly improve gt enable/disable routines

Just a cosmetic change to simplify the if statement.

Signed-off-by: Eugeni Dodonov <eugeni.dodonov@intel.com>
Reviewed-by: Ben Widawsky <ben@bwidawsk.net>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
1 file changed