kdb: cleanup unused variables missed in the original kdb merge

The BTARGS and BTSYMARG variables do not have any function in the
mainline version of kdb.

Reported-by: Tim Bird <tim.bird@am.sony.com>
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>

kernel/debug/kdb/kdb_main.c

@@ -145,7 +145,6 @@ static char *__env[] = {
 #endif
  "RADIX=16",
  "MDCOUNT=8",			/* lines of md output */
- "BTARGS=9",			/* 9 possible args in bt */
  KDB_PLATFORM_ENV,
  "DTABCOUNT=30",
  "NOSECT=1",
@@ -172,6 +171,7 @@ static char *__env[] = {
  (char *)0,
  (char *)0,
  (char *)0,
+ (char *)0,
 };
 
 static const int __nenv = (sizeof(__env) / sizeof(char *));