drm/i915: Use the precomputed value for whether to enable command parsing

commit 41736a8e3331a67445b271e73be39536c498659e upstream.

As i915.enable_cmd_parser is an unsafe option, make it read-only at
runtime. Now that it is constant, we can use the value determined during
initialisation as to whether we need the cmdparser at execbuffer time.

v2: Remove the inline for its single user, it is clear enough (and
shorter) without!

Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Jon Bloomfield <jon.bloomfield@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161124125851.6615-1-chris@chris-wilson.co.uk


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>