agp: Documentation fixes

Fix compiler warnings

  drivers/char/agp/backend.c:68: warning: Function parameter or member 'pdev' not described in 'agp_backend_acquire'
  drivers/char/agp/backend.c:93: warning: Function parameter or member 'bridge' not described in 'agp_backend_release'

by adding the necessary documentation.
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Helge Deller <deller@gmx.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20211201114645.15384-4-tzimmermann@suse.de

drivers/char/agp/backend.c

@@ -62,6 +62,7 @@ EXPORT_SYMBOL(agp_find_bridge);
 
 /**
  *	agp_backend_acquire  -  attempt to acquire an agp backend.
+ *	@pdev: the PCI device
  *
  */
 struct agp_bridge_data *agp_backend_acquire(struct pci_dev *pdev)
@@ -83,6 +84,7 @@ EXPORT_SYMBOL(agp_backend_acquire);
 
 /**
  *	agp_backend_release  -  release the lock on the agp backend.
+ *	@bridge: the AGP backend to release
  *
  *	The caller must insure that the graphics aperture translation table
  *	is read for use by another entity.