powerpc/mm: Remove a redundant test in do_page_fault()

The result of (trap == 0x400) is already in is_exec.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/fault.c

@@ -216,7 +216,7 @@ int do_page_fault(struct pt_regs *regs, unsigned long address,
 	 * bits we are interested in.  But there are some bits which
 	 * indicate errors in DSISR but can validly be set in SRR1.
 	 */
-	if (trap == 0x400)
+	if (is_exec)
 		error_code &= 0x48200000;
 	else
 		is_write = error_code & DSISR_ISSTORE;