reed_solomon: Fix kernel-doc

The current doc build warns:
./lib/reed_solomon/reed_solomon.c:287: WARNING: Unknown target name: "gfp".

This is because it misinterprets the "GFP_" that is part of the
description.  Change the description to avoid the problem.
Signed-off-by: Matthew Wilcox <willy@infradead.org>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>

lib/reed_solomon/reed_solomon.c

@@ -283,7 +283,7 @@ static struct rs_control *init_rs_internal(int symsize, int gfpoly,
  *		in index form
  *  @prim:	primitive element to generate polynomial roots
  *  @nroots:	RS code generator polynomial degree (number of roots)
- *  @gfp:	GFP_ flags for allocations
+ *  @gfp:	Memory allocation flags.
  */
 struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
 			       int nroots, gfp_t gfp)