it83xx: add support for IT81202BX and IT81302BX
it83xx: add support for IT81202BX and IT81302BX

This CL applies A version's configurations to B version.
They have the same HW except for new added function
(eg. SPI emulate eMMC "Alternative Boot Mode") on B version.

We can add new chip config option for B version in other CL
if needed.

BUG=none
BRANCH=none
TEST=Building asurada's EC image with selecting BX chip variant.
     Flashing the image into reworked asurada (change EC to IT81202BX)
     and boot to kernel.

Signed-off-by: Dino Li <338d523ecf3700bd86eb9c34d220f91911d2a18c@ite.com.tw>
Change-Id: I796a622df21842998ad8f808bfa189b924710649
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/2501802
Reviewed-by: Eric Yilun Lin <2f2733c7206ea2b76bd2db1905cc5e8a75841c48@chromium.org>

coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec,coreboot/chrome-ec