drm/i915: Introduce custom variant of module_param_named macro

As we now use same name for public module param and its local
representation we can simplify param definition macro.

Changes done with Coccinelle:

@@
declarer name module_param_named;
declarer name module_param_named_unsafe;
declarer name i915_param_named;
declarer name i915_param_named_unsafe;
identifier n;
@@

(
-module_param_named(n, i915.n,
+i915_module_param_named(n,
  ...);
|
-module_param_named_unsafe(n, i915.n,
+i915_module_param_named_unsafe(n,
 ...);
)
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20170914150805.28376-3-michal.wajdeczko@intel.com