Use new stat item/ctr getter APIs

Generated with spatch:
"""
@@
expression E1, E2;
@@
- &E2->ctr[E1]
+ rate_ctr_group_get_ctr(E2, E1)
"""

Change-Id: I2e064883ac6dafa89e41a297a886a9ebd26ce925
diff --git a/src/sgsn/sgsn_libgtp.c b/src/sgsn/sgsn_libgtp.c
index 6229217..1ac3b44 100644
--- a/src/sgsn/sgsn_libgtp.c
+++ b/src/sgsn/sgsn_libgtp.c
@@ -792,10 +792,10 @@
 		return -1;
 	}
 
-	rate_ctr_inc(&pdp->ctrg->ctr[PDP_CTR_PKTS_UDATA_OUT]);
-	rate_ctr_add(&pdp->ctrg->ctr[PDP_CTR_BYTES_UDATA_OUT], len);
-	rate_ctr_inc(&mm->ctrg->ctr[GMM_CTR_PKTS_UDATA_OUT]);
-	rate_ctr_add(&mm->ctrg->ctr[GMM_CTR_BYTES_UDATA_OUT], len);
+	rate_ctr_inc(rate_ctr_group_get_ctr(pdp->ctrg, PDP_CTR_PKTS_UDATA_OUT));
+	rate_ctr_add(rate_ctr_group_get_ctr(pdp->ctrg, PDP_CTR_BYTES_UDATA_OUT), len);
+	rate_ctr_inc(rate_ctr_group_get_ctr(mm->ctrg, GMM_CTR_PKTS_UDATA_OUT));
+	rate_ctr_add(rate_ctr_group_get_ctr(mm->ctrg, GMM_CTR_BYTES_UDATA_OUT), len);
 
 	/* It is easier to have a global count */
 	pdp->cdr_bytes_out += len;
@@ -830,10 +830,10 @@
 		return -EIO;
 	}
 
-	rate_ctr_inc(&pdp->ctrg->ctr[PDP_CTR_PKTS_UDATA_IN]);
-	rate_ctr_add(&pdp->ctrg->ctr[PDP_CTR_BYTES_UDATA_IN], npdu_len);
-	rate_ctr_inc(&mmctx->ctrg->ctr[GMM_CTR_PKTS_UDATA_IN]);
-	rate_ctr_add(&mmctx->ctrg->ctr[GMM_CTR_BYTES_UDATA_IN], npdu_len);
+	rate_ctr_inc(rate_ctr_group_get_ctr(pdp->ctrg, PDP_CTR_PKTS_UDATA_IN));
+	rate_ctr_add(rate_ctr_group_get_ctr(pdp->ctrg, PDP_CTR_BYTES_UDATA_IN), npdu_len);
+	rate_ctr_inc(rate_ctr_group_get_ctr(mmctx->ctrg, GMM_CTR_PKTS_UDATA_IN));
+	rate_ctr_add(rate_ctr_group_get_ctr(mmctx->ctrg, GMM_CTR_BYTES_UDATA_IN), npdu_len);
 
 	/* It is easier to have a global count */
 	pdp->cdr_bytes_in += npdu_len;