Staging: lustre: lnet: selftest: Made a function static.

The following patch makes a function static as it was not used by other
files.
The patch fixes the warning:
WARNING: symbol 'brw_fill_bulk' was not declared. Should it be
static?

The above warning was reported by sparse.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lnet/selftest/brw_test.c

@@ -221,7 +221,7 @@ bad_data:
 	return 1;
 }
 
-void
+static void
 brw_fill_bulk(srpc_bulk_t *bk, int pattern, __u64 magic)
 {
 	int	 i;