checkpatch: update section keywords

As of commit bd721ea7 ("treewide: replace obsolete _refok by
__ref"), __init_refok no longer exists, so it can be removed.  While at
it, add the modern variants that were still missing.

Link: http://lkml.kernel.org/r/20180706084205.26367-1-geert+renesas@glider.beSigned-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Acked-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

scripts/checkpatch.pl

@@ -346,9 +346,10 @@ our $Sparse	= qr{
 			__force|
 			__iomem|
 			__must_check|
-			__init_refok|
 			__kprobes|
 			__ref|
+			__refconst|
+			__refdata|
 			__rcu|
 			__private
 		}x;