flashchips.c: remove WREN from GD25Q256D enter 4BA sequence

As noted in a comment on
`commit 86fc9cf7ab221bc54ef6f10252e296fc2d7a22d2`, the GD25Q256D
datasheet indicates that the chip does not require a WREN command to
enter 4BA mode.

Testing has confirmed that a WREN command is not required, so change the
flashchip feature flags from FEATURE_4BA_WREN to FEATURE_4BA.

Ticket: https://ticket.coreboot.org/issues/356

BUG=none
BRANCH=none
TEST=read/write/erase/verify GD25Q256D flash with FT2232H programmer
TEST=called spi_enter_exit_4ba(true), dumped registers, checked ADS=1.

Original-Signed-off-by: Nikolai Artemiev <nartemiev@google.com>
Original-Reviewed-on: https://review.coreboot.org/c/flashrom/+/70342
Original-Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Original-Reviewed-by: Anastasia Klimchuk <aklm@chromium.org>
Original-Reviewed-by: Nico Huber <nico.h@gmx.de>
(cherry picked from commit 7f3c3f5c4807f4f3c0c2de405189e86b3f8d77a3)

Change-Id: I96e48933f33c52c0d10a0d4cb7f7e07c1fceab99
Signed-off-by: Evan Benn <evanbenn@google.com>
---
M flashchips.c
1 file changed, 33 insertions(+), 1 deletion(-)