atmel: Remove open-coded and wrong strcasecmp

The kernel's string library does in fact have strcasecmp, at least
since ded220bd8f08 ("[STRING]: Move strcasecmp/strncasecmp to
lib/string.c"). Moreover, this open-coded version is in fact wrong: If
the strings only differ in their last character, a and b have already
been incremented to point to the terminating NUL bytes, so they would
wrongly be treated as equal.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/atmel.c

@@ -45,7 +45,6 @@
 #include <linux/ptrace.h>
 #include <linux/slab.h>
 #include <linux/string.h>
-#include <linux/ctype.h>
 #include <linux/timer.h>
 #include <asm/byteorder.h>
 #include <asm/io.h>
@@ -2699,16 +2698,7 @@ static int atmel_ioctl(struct net_device *dev, struct ifreq *rq, int cmd)
 		domain[REGDOMAINSZ] = 0;
 		rc = -EINVAL;
 		for (i = 0; i < ARRAY_SIZE(channel_table); i++) {
-			/* strcasecmp doesn't exist in the library */
-			char *a = channel_table[i].name;
-			char *b = domain;
-			while (*a) {
-				char c1 = *a++;
-				char c2 = *b++;
-				if (tolower(c1) != tolower(c2))
-					break;
-			}
-			if (!*a && !*b) {
+			if (!strcasecmp(channel_table[i].name, domain)) {
 				priv->config_reg_domain = channel_table[i].reg_domain;
 				rc = 0;
 			}