include/linux/gfp.h: fix ___GFP_NOLOCKDEP value

Igor Stoppa has noticed that __GFP_NOLOCKDEP can use a lower bit.  At
the time commit 7e7844226f10 ("lockdep: allow to disable reclaim lockup
detection") was written we still had __GFP_OTHER_NODE but I have removed
it in commit 41b6167e8f74 ("mm: get rid of __GFP_OTHER_NODE") and forgot
to lower the bit value.

The current value is outside of __GFP_BITS_SHIFT so it cannot be used
actually.

Fixes: 7e7844226f10 ("lockdep: allow to disable reclaim lockup detection")
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reported-by: Igor Stoppa <igor.stoppa@nokia.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

include/linux/gfp.h

@@ -41,7 +41,7 @@ struct vm_area_struct;
 #define ___GFP_WRITE		0x800000u
 #define ___GFP_KSWAPD_RECLAIM	0x1000000u
 #ifdef CONFIG_LOCKDEP
-#define ___GFP_NOLOCKDEP	0x4000000u
+#define ___GFP_NOLOCKDEP	0x2000000u
 #else
 #define ___GFP_NOLOCKDEP	0
 #endif