microblaze: invoke oom-killer from page fault

As explained in commit 1c0fe6e3, we want to call the architecture independent
oom killer when getting an unexplained OOM from handle_mm_fault, rather than
simply killing current.

Cc: microblaze-uclinux@itee.uq.edu.au
Cc: Michal Simek <monstr@monstr.eu>
Cc: linux-arch@vger.kernel.org
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Michal Simek <monstr@monstr.eu>

arch/microblaze/mm/fault.c

@@ -273,16 +273,11 @@ bad_area_nosemaphore:
  * us unable to handle the page fault gracefully.
  */
 out_of_memory:
-	if (current->pid == 1) {
-		yield();
-		down_read(&mm->mmap_sem);
-		goto survive;
-	}
 	up_read(&mm->mmap_sem);
-	printk(KERN_WARNING "VM: killing process %s\n", current->comm);
-	if (user_mode(regs))
-		do_exit(SIGKILL);
+	if (!user_mode(regs))
 		bad_page_fault(regs, address, SIGKILL);
+	else
+		pagefault_out_of_memory();
 	return;
 
 do_sigbus: