gprs: Improve loglevels and log messages for SGSN

Many log levels were DEBUG without any good reason. Also where possible
the details of the MM or PDP context are now logged with LOGMM/PDPCTXP.
diff --git a/openbsc/src/gprs/gprs_sgsn.c b/openbsc/src/gprs/gprs_sgsn.c
index f92b2de..0c15619 100644
--- a/openbsc/src/gprs/gprs_sgsn.c
+++ b/openbsc/src/gprs/gprs_sgsn.c
@@ -254,7 +254,7 @@
 	 * sgsn_libgtp:cb_data_ind() */
 	if (pdp->lib) {
 		struct pdp_t *lib = pdp->lib;
-		LOGP(DGPRS, LOGL_NOTICE, "freeing PDP context that still "
+		LOGPDPCTXP(LOGL_NOTICE, pdp, "freeing PDP context that still "
 		     "has a libgtp handle attached to it, this shouldn't "
 		     "happen!\n");
 		osmo_generate_backtrace();
@@ -376,7 +376,7 @@
 		gsm48_tx_gsm_deact_pdp_req(pdp, GSM_CAUSE_NET_FAIL);
 	else  {
 		/* FIXME: GPRS paging in case MS is SUSPENDED */
-		LOGP(DGPRS, LOGL_NOTICE, "Hard-dropping PDP ctx due to GGSN "
+		LOGPDPCTXP(LOGL_NOTICE, pdp, "Hard-dropping PDP ctx due to GGSN "
 			"recovery\n");
 		/* FIXME: how to tell this to libgtp? */
 		sgsn_pdp_ctx_free(pdp);