lib/kstrtox.c: delete end-of-string test

Standard "while (*s)" test is unnecessary because NUL won't pass
valid-digit test anyway.  Save one branch per parsed character.

Link: http://lkml.kernel.org/r/20170514193756.GA32563@avx2Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

lib/kstrtox.c

@@ -51,7 +51,7 @@ unsigned int _parse_integer(const char *s, unsigned int base, unsigned long long
 
 	res = 0;
 	rv = 0;
-	while (*s) {
+	while (1) {
 		unsigned int val;
 
 		if ('0' <= *s && *s <= '9')