flashchips: Mark Atmel AT25DF161 as tested

As per Konstantin on 2018-06-08 via mailing list.

Change-Id: I75fb4b17cf330451489811ae9303cbb33ebcb183
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/28814
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 e5f78aa..c50fd30 100644
--- a/flashchips.c
+++ b/flashchips.c
@@ -1679,7 +1679,7 @@
 		.total_size	= 2048,
 		.page_size	= 256,
 		.feature_bits	= FEATURE_WRSR_WREN,
-		.tested		= TEST_OK_PROBE,
+		.tested		= TEST_OK_PREW,
 		.probe		= probe_spi_rdid,
 		.probe_timing	= TIMING_ZERO,
 		.block_erasers	=