frv: kill used but uninitialized variable

Commit 6afe1a1f ("PM: Remove legacy PM") removed the initialization
of retval, causing:

  arch/frv/kernel/pm.c: In function 'sysctl_pm_do_suspend':
  arch/frv/kernel/pm.c:165:5: warning: 'retval' may be used uninitialized in this function [-Wuninitialized]

Remove the variable completely to fix this, and convert to a proper
switch (...) { ... } construct to improve readability.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Cc: David Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

arch/frv/kernel/pm.c

@@ -153,23 +153,22 @@ static int user_atoi(char __user *ubuf, size_t len)
 static int sysctl_pm_do_suspend(ctl_table *ctl, int write,
 				void __user *buffer, size_t *lenp, loff_t *fpos)
 {
-	int retval, mode;
+	int mode;
 
 	if (*lenp <= 0)
 		return -EIO;
 
 	mode = user_atoi(buffer, *lenp);
-	if ((mode != 1) && (mode != 5))
-		return -EINVAL;
+	switch (mode) {
+	case 1:
+	    return pm_do_suspend();
 
-	if (retval == 0) {
-		if (mode == 5)
-		    retval = pm_do_bus_sleep();
-		else
-		    retval = pm_do_suspend();
-	}
+	case 5:
+	    return pm_do_bus_sleep();
 
-	return retval;
+	default:
+	    return -EINVAL;
+	}
 }
 
 static int try_set_cmode(int new_cmode)