chip/npcx: Add support for chip_save_reset_flags
chip/npcx: Add support for chip_save_reset_flags

Add and export chip_save_reset_flags to allow boards to use this
function when required.

BUG=chrome-os-partner:61883
BRANCH=None
TEST=Compiles successfully for poppy.

Change-Id: I6f96bc61135fc4e3abb62a01d47c2cba8eb45b60
Signed-off-by: Furquan Shaikh <6be5c96c464778f89679b1062a2e0a6af93d2aa5@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/431191
Reviewed-by: Aaron Durbin <af0622ab041e8b0f8e5819838dcc93898196e71f@chromium.org>
Reviewed-by: Nicolas Boichat <f3daba1cdc403799935674d3cd4b0e5bd1804232@chromium.org>

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