flashchips: Enable unbounded read on W25Q256

Mark unbounded read as supported and tested as I verified it
on a W25Q256 chip.

BUG=b:117318564
BRANCH=none
TEST=test read on W25Q256

Change-Id: I6f1cf505b5cc9bef8930868e566a7fc62034889e
Signed-off-by: Duncan Laurie <dlaurie@google.com>
Reviewed-on: https://chromium-review.googlesource.com/1273627
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Furquan Shaikh <furquan@chromium.org>
1 file changed