edge: Support EGPRS in packet uplink assignment message

Currently the Encoding::write_packet_uplink_assignment method only
supports the GPRS variant of the message.

This commit adds the missing EGPRS variant to the encoder.

Sponsored-by: On-Waves ehf
diff --git a/src/encoding.h b/src/encoding.h
index 0004c42..ac66838 100644
--- a/src/encoding.h
+++ b/src/encoding.h
@@ -48,7 +48,7 @@
 			bitvec * dest, uint8_t old_tfi,
 			uint8_t old_downlink, uint32_t tlli, uint8_t use_tlli, 
 			struct gprs_rlcmac_ul_tbf *tbf, uint8_t poll, uint8_t alpha,
-			uint8_t gamma, int8_t ta_idx);
+			uint8_t gamma, int8_t ta_idx, int8_t use_egprs);
 
 	static void write_packet_downlink_assignment(RlcMacDownlink_t * block, uint8_t old_tfi,
 			uint8_t old_downlink, struct gprs_rlcmac_tbf *tbf, uint8_t poll,