x86: mm: fix VM_FAULT_RETRY handling

My commit 26178ec11ef3 ("x86: mm: consolidate VM_FAULT_RETRY handling")
had a really stupid typo: the FAULT_FLAG_USER bit is in the 'flags'
variable, not the 'fault' variable. Duh,

The one silver lining in this is that Dave finding this at least
confirms that trinity actually triggers this special path easily, in a
way normal use does not.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/mm/fault.c

@@ -1247,7 +1247,7 @@ __do_page_fault(struct pt_regs *regs, unsigned long error_code,
 		}
 
 		/* User mode? Just return to handle the fatal exception */
-		if (fault & FAULT_FLAG_USER)
+		if (flags & FAULT_FLAG_USER)
 			return;
 
 		/* Not returning to user mode? Handle exceptions or die: */