lib:vsprintf: reduce scope of pack_hex_byte

pack_hex_byte is only used when CONFIG_CMD_NET is
defined so limit it to that scope. This prevents
a clang warning.

Signed-off-by: Jeroen Hofstee <jeroen@myspectrum.nl>
diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 60874da..7ec758e 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -28,17 +28,6 @@
 /* some reluctance to put this into a new limits.h, so it is here */
 #define INT_MAX		((int)(~0U>>1))
 
-static const char hex_asc[] = "0123456789abcdef";
-#define hex_asc_lo(x)   hex_asc[((x) & 0x0f)]
-#define hex_asc_hi(x)   hex_asc[((x) & 0xf0) >> 4]
-
-static inline char *pack_hex_byte(char *buf, u8 byte)
-{
-	*buf++ = hex_asc_hi(byte);
-	*buf++ = hex_asc_lo(byte);
-	return buf;
-}
-
 unsigned long simple_strtoul(const char *cp, char **endp,
 				unsigned int base)
 {
@@ -434,6 +423,17 @@
 }
 
 #ifdef CONFIG_CMD_NET
+static const char hex_asc[] = "0123456789abcdef";
+#define hex_asc_lo(x)	hex_asc[((x) & 0x0f)]
+#define hex_asc_hi(x)	hex_asc[((x) & 0xf0) >> 4]
+
+static inline char *pack_hex_byte(char *buf, u8 byte)
+{
+	*buf++ = hex_asc_hi(byte);
+	*buf++ = hex_asc_lo(byte);
+	return buf;
+}
+
 static char *mac_address_string(char *buf, char *end, u8 *addr, int field_width,
 				int precision, int flags)
 {