splice07: Whitelist /dev/zero on pipe write

/dev/zero on pipe write started to succeeded on kernel 6.7 due
commit 1b057bd800c3 ("drivers/char/mem: implement splice() for
/dev/zero, /dev/full").

This is just a quick fix before upcoming LTP release, we should write a
separate test to test 1b057bd800c3 after the release

Link: https://lore.kernel.org/ltp/20240125155107.430656-1-pvorel@suse.cz/
Reviewed-by: Martin Doucha <mdoucha@suse.cz>
Reviewed-by: Cyril Hrubis <chrubis@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Petr Vorel <pvorel@suse.cz>

Author: pevik

testcases/kernel/syscalls/splice/splice07.c

@@ -38,6 +38,7 @@ static void check_splice(struct tst_fd *fd_in, struct tst_fd *fd_out)
 	if (fd_out->type == TST_FD_PIPE_WRITE) {
 		switch (fd_in->type) {
 		/* While these combinations succeeed */
+		case TST_FD_DEV_ZERO:
 		case TST_FD_FILE:
 		case TST_FD_MEMFD:
 			return;