flashchips: Mark Winbond W25Q40BW as tested

As per `The_Raven Raven` on the mailing list.

The tested chip was `W25Q40.W`, but it was later renamed to `W25Q40BW`
when the `W25Q40EW` was added.

Change-Id: I624adef2c5b4dd83f0ce93d6069e315fc407db19
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/28824
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 dcba427..f4b5e8d 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -15351,7 +15351,7 @@
 		.page_size	= 256,
 		/* OTP: 256B total; read 0x48; write 0x42, erase 0x44, read ID 0x4B */
 		.feature_bits	= FEATURE_WRSR_WREN | FEATURE_OTP,
-		.tested		= TEST_UNTESTED,
+		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=