Check for the ES9018K2M dac in the bootloader for
hw1/hw2 devices. Assume that all devices newer than
hw2 have ES9018K2M DAC unconditionally.
All devices will now report the correct hw revision
in the debug menu under Device Data.
Add devicedata.version field, current version 0.
Rename device_data.lcd_version to device_data.hw_rev.
hw2 devices with older bootloaders which ID as hw1 are special-
cased to keep using hwvol on them. They should still upgrade though.
Change-Id: If0fd5ce3bc6e85e511047721ec18e42fb89312e7