lib: parser: clean up kernel-doc

lib: parser: clean up kernel-doc

Mark match_uint() as kernel-doc notation since it is already fully
annotated as such.  Use % prefix on constants in kernel-doc comments.
Convert function return descriptions to use the "Return:" kernel-doc
notation.

Link: https://lkml.kernel.org/r/20210407034514.5651-1-rdunlap@infradead.org
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>