powerpc: Simplify do_sigbus

Exit out early for a kernel fault, avoiding indenting of
most of the function.
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/fault.c

@@ -120,7 +120,9 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address)
 
 	up_read(&current->mm->mmap_sem);
 
-	if (user_mode(regs)) {
+	if (!user_mode(regs))
+		return MM_FAULT_ERR(SIGBUS);
+
 	current->thread.trap_nr = BUS_ADRERR;
 	info.si_signo = SIGBUS;
 	info.si_errno = 0;
@@ -128,8 +130,6 @@ static int do_sigbus(struct pt_regs *regs, unsigned long address)
 	info.si_addr = (void __user *)address;
 	force_sig_info(SIGBUS, &info, current);
 	return MM_FAULT_RETURN;
-	}
-	return MM_FAULT_ERR(SIGBUS);
 }
 
 static int mm_fault_error(struct pt_regs *regs, unsigned long addr, int fault)