msc_a,vlr: rename ciphering_required to try_ciphering

Clarify the name to avoid confusion in upcoming patches.

This function actually returns whether any ciphering mode besides A5/0
is enabled, and does not imply that ciphering is mandatory. A5/0 may
well be allowed when this function returns true.

Related: OS#4830
Change-Id: Ia55085e3b36feb275bcf92fc91a4be7d1c24a6b9
diff --git a/src/libmsc/msc_a.c b/src/libmsc/msc_a.c
index f00fb11..fad5b77 100644
--- a/src/libmsc/msc_a.c
+++ b/src/libmsc/msc_a.c
@@ -106,7 +106,7 @@
 	return fi->priv;
 }
 
-bool msc_a_require_ciphering(const struct msc_a *msc_a)
+bool msc_a_try_ciphering(const struct msc_a *msc_a)
 {
 	struct gsm_network *net = msc_a_net(msc_a);
 	bool is_utran = (msc_a->c.ran->type == OSMO_RAT_UTRAN_IU);