drm: Replace filp in ioctl arguments with drm_file *file_priv.

As a fallout, replace filp storage with file_priv storage for "unique
identifier of a client" all over the DRM.  There is a 1:1 mapping, so this
should be a noop.  This could be a minor performance improvement, as everyth
on Linux dereferenced filp to get file_priv anyway, while only the mmap ioct
went the other direction.

Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/i915_irq.c b/drivers/char/drm/i915_irq.c
index 470e7aa..36be24e 100644
--- a/drivers/char/drm/i915_irq.c
+++ b/drivers/char/drm/i915_irq.c
@@ -362,7 +362,7 @@
 	drm_i915_irq_emit_t emit;
 	int result;
 
-	LOCK_TEST_WITH_RETURN(dev, filp);
+	LOCK_TEST_WITH_RETURN(dev, file_priv);
 
 	if (!dev_priv) {
 		DRM_ERROR("%s called with no initialization\n", __FUNCTION__);