tests/alloc: fix implicit conversion from 'double' to 'int8_t'

Looks pretty much like a typo. Both '-1' and '.' symbols are
neighbours in QWERTZ keyboard layout, so it must be -1.

Found by Clang [-Wliteral-conversion].

Change-Id: Id4eb2dcc3b44e18096c7b94efb7260e2400c596b
diff --git a/tests/alloc/AllocTest.cpp b/tests/alloc/AllocTest.cpp
index 123f879..2fdee3f 100644
--- a/tests/alloc/AllocTest.cpp
+++ b/tests/alloc/AllocTest.cpp
@@ -309,7 +309,7 @@
 
 	tfi = the_bts.tfi_find_free(GPRS_RLCMAC_UL_TBF, &trx_no, -1);
 	OSMO_ASSERT(tfi >= 0);
-	ul_tbf = tbf_alloc_ul_tbf(bts, NULL, .1, ms_class, 0, false);
+	ul_tbf = tbf_alloc_ul_tbf(bts, NULL, -1, ms_class, 0, false);
 	if (!ul_tbf)
 		return false;