lustre: ptlrpc: add "ptlrpc_internal.h" to sec_gc.c

ptlrpc_internal.h contains the prototypes for sptlrpc_gc_init() and
sptlrpc_gc_fini(), which are defined in sec_gc.c.

This removes the following sparse warnings:

drivers/staging/lustre/lustre/ptlrpc/sec_gc.c:217:5: warning: symbol 'sptlrpc_gc_init' was not declared. Should it be static?
drivers/staging/lustre/lustre/ptlrpc/sec_gc.c:241:6: warning: symbol 'sptlrpc_gc_fini' was not declared. Should it be static?
Signed-off-by: Spencer Baugh <sbaugh@andrew.cmu.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/ptlrpc/sec_gc.c

@@ -47,6 +47,8 @@
 #include "../include/lustre_net.h"
 #include "../include/lustre_sec.h"
 
+#include "ptlrpc_internal.h"
+
 #define SEC_GC_INTERVAL (30 * 60)