Delete eeprom callbacks for platforms which no longer use it

With "eeprom map" command gone, the only remaining usages of eeprom
callbacks in mosys are:

- In cros_spi_flash_nvram_cb, for reading/writing VBNV from flashrom.
- For platforms which read/write the firmware eventlog from
  flash (ARM).

This means there's quite a few platforms we can start removing this
callback from.

BUG=chromium:990438
TEST=compiles

Change-Id: I90b6d7732c46d694baac3aaaeb3857bdb3fed208
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/mosys/+/2216394
Tested-by: Jack Rosenthal <jrosenth@chromium.org>
Reviewed-by: Victor Ding <victording@chromium.org>
Commit-Queue: Jack Rosenthal <jrosenth@chromium.org>
24 files changed