LTC2942 is pin compatible with LTC2941 providing few more registers
holding information about battery voltage and temperature. It can
be runtime detected using bit A7 in the Status register.

PATCH 1/2 defines LTC2942 registers with no functional changes
while 2/2 does actually the job.

I'm not sure, whenever splitting support into two patches makes
sense, but it just makes reviewing easier. I'd happily
squash patches together.

Comments welcome,
	ladis