x86/boot: Fix a sanity check in printf.c

Prior to 9b706aee ("x86: trivial printk optimizations") this was
36 because it had 26 characters and 10 digits but now it's just
16 hex digits so the sanity check needs updated.

This function is always called with a valid "base" so it doesn't
make a difference to how the kernel works, it's just a cleanup.
Reported-by: Alexey Petrenko <alexey.petrenko@oracle.com>
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>

arch/x86/boot/printf.c

@@ -55,7 +55,7 @@ static char *number(char *str, long num, int base, int size, int precision,
 	locase = (type & SMALL);
 	if (type & LEFT)
 		type &= ~ZEROPAD;
-	if (base < 2 || base > 36)
+	if (base < 2 || base > 16)
 		return NULL;
 	c = (type & ZEROPAD) ? '0' : ' ';
 	sign = 0;