tag: Remove unnecessary 'const' qualifier

Compilation process was failing due 'const' qualifier ignored,
triggered by the ignored-qualifier flag.

Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
diff --git a/src/tag.c b/src/tag.c
index 44646d5..91cd255 100644
--- a/src/tag.c
+++ b/src/tag.c
@@ -169,7 +169,7 @@
 	return type;
 }
 
-static const uint8_t uid_array(struct near_tag *tag, uint8_t **uid)
+static uint8_t uid_array(struct near_tag *tag, uint8_t **uid)
 {
 	if (tag->nfcid_len) {
 		DBG("NFCID: ");