ANDROID: rtc-palmas: correct for bcd year

Replace bcd2bin and bin2bcd with one that maps years 1970 to 2129
in a pattern that works with the underlying hardware.

The only transition that does not work correctly for this rtc clock
is the transition from 2099 to 2100, it proceeds to 2000. The rtc
clock retains and transitions the year correctly in all other
circumstances.

Signed-off-by: Mark Salyzyn <salyzyn@google.com>
Bug: 26346842
Change-Id: I99f784d1f2b8ce063b3713df0914c7d8814a4e35