sysctl: don't use own implementation of hex_to_bin()

Remove own implementation of hex_to_bin().

Signed-off-by: Andy Shevchenko <[e-mail]>
Cc: Eric W. Biederman <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

kernel/sysctl_binary.c

···
 #include <linux/file.h>
 #include <linux/ctype.h>
 #include <linux/netdevice.h>
+#include <linux/kernel.h>
 #include <linux/slab.h>
 
 #ifdef CONFIG_SYSCTL_SYSCALL
···
 	return result;
 }
 
-static unsigned hex_value(int ch)
-{
-	return isdigit(ch) ? ch - '0' : ((ch | 0x20) - 'a') + 10;
-}
-
 static ssize_t bin_uuid(struct file *file,
 	void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
 {
···
 			if (!isxdigit(str[0]) || !isxdigit(str[1]))
 				goto out;
 
-			uuid[i] = (hex_value(str[0]) << 4) | hex_value(str[1]);
+			uuid[i] = (hex_to_bin(str[0]) << 4) |
+					hex_to_bin(str[1]);
 			str += 2;
 			if (*str == '-')
 				str++;