staging: lustre: lnet: make brw_inject_one_error() static

It's not used anywhere outside of brw_test.c file.
Highlighted by sparse.
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

@@ -136,7 +136,7 @@ brw_client_init(struct sfw_test_instance *tsi)
 	return 0;
 }
 
-int brw_inject_one_error(void)
+static int brw_inject_one_error(void)
 {
 	struct timespec64 ts;