Move IMSI into test parameters

This makes test routines more flexible and allows to easier re-use them
for tests with different IMSIs.

Change-Id: I74d46fdb7e87dc04c6b82a0b6f3ce6bef60bde58
Related: OS#2864
diff --git a/tests/msc_vlr/msc_vlr_tests.h b/tests/msc_vlr/msc_vlr_tests.h
index ee26ac4..eaec340 100644
--- a/tests/msc_vlr/msc_vlr_tests.h
+++ b/tests/msc_vlr/msc_vlr_tests.h
@@ -122,7 +122,7 @@
 	int run_test_nr;
 };
 
-typedef void (* msc_vlr_test_func_t )(void);
+typedef void (* msc_vlr_test_func_t )(const char *);
 extern msc_vlr_test_func_t msc_vlr_tests[];
 
 struct msgb *msgb_from_hex(const char *label, uint16_t size, const char *hex);