flashchips.c: Mark MT25QL256 as tested

As mentioned in mail from Bernd.Stoeferle@elbitsystems-de.com on 22.12.2020.

Change-Id: Ie49332333f49a40f7bd8f3b5e42a8e2ad6995618
Signed-off-by: Simon Buhrow <simon.buhrow@posteo.de>
Reviewed-on: https://review.coreboot.org/c/flashrom/+/50720
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
diff --git a/flashchips.c b/flashchips.c
index ef5ea5e..950f09b 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -11644,7 +11644,7 @@
 		/* supports SFDP */
 		/* OTP: 64B total; read 0x4B, write 0x42 */
 		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP | FEATURE_4BA_WREN,
-		.tested		= TEST_UNTESTED,
+		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=