drivers/google/cros_ec: remove cros_ec_get_firmware_rom_size

Function is now unused.

BUG=chromium:990438
TEST=compiles

Change-Id: I0dab8c46db6da95e1ddea3f94f73751169681c59
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/mosys/+/2469471
Tested-by: Jack Rosenthal <jrosenth@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Paul Fagerburg <pfagerburg@chromium.org>
2 files changed