tests: Clear ID cache before trying to fetch chip ID a second time

Without that, the code never calls into spi_send_command (because
everything's known already) and so the expected return values are
never returned.

Change-Id: Iba6a56774ce5b51e0f7072b4600a9479cdabf8c7
Signed-off-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/45431
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

tests/spi25.c

@@ -129,6 +129,7 @@ void probe_spi_res2_test_success(void **state)
 	(void) state; /* unused */
 
 	/* setup initial test state. */
+	clear_spi_id_cache();
 	struct flashctx flashctx = { .chip = &mock_chip };
 	expect_memory(__wrap_spi_send_command, flash,
 			&flashctx, sizeof(flashctx));