rename files acc_ramp.* -> acc.c*

With upcoming next commit, the file will contain far more code that
simply ramping, so rename it to be more generic.

Change-Id: I8c368ab87e264439dea4ccf556821a44664cdbb0
diff --git a/tests/nanobts_omlattr/Makefile.am b/tests/nanobts_omlattr/Makefile.am
index 67d059f..1cdcc50 100644
--- a/tests/nanobts_omlattr/Makefile.am
+++ b/tests/nanobts_omlattr/Makefile.am
@@ -24,7 +24,7 @@
 
 nanobts_omlattr_test_LDADD = \
 	$(top_builddir)/src/osmo-bsc/abis_nm.o \
-	$(top_builddir)/src/osmo-bsc/acc_ramp.o \
+	$(top_builddir)/src/osmo-bsc/acc.o \
 	$(top_builddir)/src/osmo-bsc/bts_ipaccess_nanobts_omlattr.o \
 	$(top_builddir)/src/osmo-bsc/bts.o \
 	$(top_builddir)/src/osmo-bsc/bts_trx.o \