drm/gem-shmem: Fix typos in documentation

Fix the compile-time warnings

Warning: drm_gem_shmem_helper.c:104 function parameter 'shmem' not described in 'drm_gem_shmem_init'
Warning: drm_gem_shmem_helper.c:104 function parameter 'size' not described in 'drm_gem_shmem_init'

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Fixes: e3f4bda ("drm/gem/shmem: Extract drm_gem_shmem_init() from drm_gem_shmem_create()")
Link: https://patch.msgid.link/20251209140141.94407-2-tzimmermann@suse.de

Author: tdz

drivers/gpu/drm/drm_gem_shmem_helper.c

@@ -96,7 +96,8 @@ static int __drm_gem_shmem_init(struct drm_device *dev, struct drm_gem_shmem_obj
 /**
  * drm_gem_shmem_init - Initialize an allocated object.
  * @dev: DRM device
- * @obj: The allocated shmem GEM object.
+ * @shmem: The allocated shmem GEM object.
+ * @size: Buffer size in bytes
  *
  * Returns:
  * 0 on success, or a negative error code on failure.