power_supply: cleanup of the OLPC battery driver

Move portions of the massive switch statement into functions.  The layout of
this thing has already caused one bug (a break in the wrong place), it needed
to shrink.

Signed-off-by: Andres Salomon <dilinger@debian.org>
Cc: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>