rockchip: veyron: Enable Winbond SPI flash

Some veyron boards seem to have Winbond SPI flash chips instead of
GigaDevice ones. At the very least, coreboot builds for veyron boards
have them enabled [1]. Enable support for them here as well.

[1] https://review.coreboot.org/c/coreboot/+/9719



Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>