flashchips: Mark Winbond W25Q256.V as tested

As per Richard Hughes via the mailing list.

Change-Id: Ic562a65d1a7d394f9d2c3980833d10a87bd9358a
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/28816
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>
diff --git a/flashchips.c b/flashchips.c
index 3d0d898..7a19054 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -15273,7 +15273,7 @@
 		/* FOUR_BYTE_ADDR: supports 4-bytes addressing mode */
 		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP | FEATURE_4BA_ENTER_WREN
 			| FEATURE_4BA_EXT_ADDR | FEATURE_4BA_READ | FEATURE_4BA_FAST_READ,
-		.tested		= TEST_UNTESTED,
+		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=