remove SI3 and SI4 rest octets

As Dieter has pointed out, we currently send incorrect information
in the rest octets, particularly about our GPRS capability.  Since
the format of the rest octets is highly complex, and we don't
actually need any of those features yet, we might just fill them
with padding.
diff --git a/openbsc/src/bsc_hack.c b/openbsc/src/bsc_hack.c
index 13438b9..384da54 100644
--- a/openbsc/src/bsc_hack.c
+++ b/openbsc/src/bsc_hack.c
@@ -696,14 +696,7 @@
     cell not barred for access
     call reestablishment not allowed
     Access Control Class = 0000
-  SI 3 Rest Octets
-    Cell Bar Qualify (CBQ): 0
-    Cell Reselect Offset = 0 dB
-    Temporary Offset = 0 dB
-    Penalty Time = 20 s
-    System Information 2ter Indicator (2TI): 0 = not available
-    Early Classmark Sending Control (ECSC):  0 = forbidden
-    Scheduling Information is not sent in SYSTEM INFORMATION TYPE 9 on the BCCH
+  SI 3 Rest Octets (not present)
 */
 static u_int8_t si3[] = {
 	/* header */0x49, 0x06, 0x1B,
@@ -713,7 +706,7 @@
 	/* option*/0x28,
 	/* selection*/0x62, 0x00,
 	/* rach */0xD5, 0x00, 0x00,
-	/* reset*/0x80, 0x00, 0x00, 0x2B
+	/* rest */ 0x2B, 0x2B, 0x2B, 0x2B
 };
 
 /*
@@ -734,24 +727,20 @@
     cell not barred for access
     call reestablishment not allowed
     Access Control Class = 0000
-  Channel Description
+  CBCH Channel Description
     Type = SDCCH/4[2]
     Timeslot Number: 0
     Training Sequence Code: 7h
     ARFCN: 1
-  SI Rest Octets
-    Cell Bar Qualify (CBQ): 0
-    Cell Reselect Offset = 0 dB
-    Temporary Offset = 0 dB
-    Penalty Time = 20 s
+  SI Rest Octets (not present) 
 */
 static u_int8_t si4[] = {
 	/* header */0x41, 0x06, 0x1C,
 	/* lai */0x00, 0xF1, 0x10, 0x00, 0x01,
 	/* sel */0x62, 0x00,
 	/* rach*/0xD5, 0x00, 0x00,
-	/* var */0x64, 0x30, 0xE0, HARDCODED_ARFCN/*0x01*/, 0x80, 0x00, 0x00,
-	0x2B, 0x2B, 0x2B
+	/* cbch chan desc */ 0x64, 0x30, 0xE0, HARDCODED_ARFCN/*0x01*/,
+	/* rest octets */ 0x2B, 0x2B, 0x2B, 0x2B, 0x2B, 0x2B
 };
 
 /*