si/test: Merge si tests into gsm48 tests

Currently tests covering features of the GSM 04.08 specification are
spread over the si and gsm0408 subdirs in tests.

This commit merges all tests from 'si' into 'gsm0408' and removes the
'si' test sub-directory.

Sponsored-by: On-Waves ehf
diff --git a/openbsc/tests/gsm0408/gsm0408_test.ok b/openbsc/tests/gsm0408/gsm0408_test.ok
index a92b879..5458669 100644
--- a/openbsc/tests/gsm0408/gsm0408_test.ok
+++ b/openbsc/tests/gsm0408/gsm0408_test.ok
@@ -2,6 +2,26 @@
 Testing parsing and generating TMSI/IMSI
 hex: 17 08 99 78 56 34 12 90 78 36 
 hex: 17 09 91 78 56 34 12 90 78 56 f4 
+Element is: 2 => freqs[i] = 121
+Element is: 2 => freqs[i] = 1
+Element is: 0 => freqs[i] = 68
+w[0]=122
+w[1]=2
+w[2]=69
+w[3]=204
+w[4]=75
+w[5]=66
+w[6]=60
+w[7]=70
+w[8]=83
+w[9]=3
+w[10]=24
+w[11]=67
+w[12]=54
+w[13]=64
+w[14]=70
+w[15]=9
+Range512: 89 4b 2a 95 65 95 55 2c a9 55 aa 55 6a 95 59 55 
 Range test 0: range 511, num ARFCNs 12
 chan_list = 88 00 98 34 85 36 7c 50 22 dc 5e ec 00 00 00 00 
 Decoded freqs 12 (expected 12)