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/drm_vm.c b/drivers/char/drm/drm_vm.c
index 68e36e5..e8d50af 100644
--- a/drivers/char/drm/drm_vm.c
+++ b/drivers/char/drm/drm_vm.c
@@ -463,7 +463,7 @@
 /**
  * mmap DMA memory.
  *
- * \param filp file pointer.
+ * \param file_priv DRM file private.
  * \param vma virtual memory area.
  * \return zero on success or a negative number on failure.
  *
@@ -533,7 +533,7 @@
 /**
  * mmap DMA memory.
  *
- * \param filp file pointer.
+ * \param file_priv DRM file private.
  * \param vma virtual memory area.
  * \return zero on success or a negative number on failure.
  *