Split identity_lv param into mi+mi_len

It's not really needed to have those together in some function calls,
and makes it more difficult to follow the code. Furthermore, new callers
not having content already aligned (len+value) will be using these
functions in forthcoming commits.

Change-Id: Ifb9d3997bfb74b35366c3d1bc51ce458f19abf16
diff --git a/src/pdch.cpp b/src/pdch.cpp
index da221f4..e15af2c 100644
--- a/src/pdch.cpp
+++ b/src/pdch.cpp
@@ -251,14 +251,15 @@
 	return msg;
 }
 
-bool gprs_rlcmac_pdch::add_paging(uint8_t chan_needed, uint8_t *identity_lv)
+bool gprs_rlcmac_pdch::add_paging(uint8_t chan_needed, const uint8_t *mi, uint8_t mi_len)
 {
 	struct gprs_rlcmac_paging *pag = talloc_zero(tall_pcu_ctx, struct gprs_rlcmac_paging);
 	if (!pag)
 		return false;
 
 	pag->chan_needed = chan_needed;
-	memcpy(pag->identity_lv, identity_lv, identity_lv[0] + 1);
+	pag->identity_lv[0] = mi_len;
+	memcpy(&pag->identity_lv[1], mi, mi_len);
 
 	llist_add(&pag->list, &paging_list);