power: supply: sbs-battery: add PEC support

SBS batteries optionally have support for PEC. This enables
PEC handling based on the implemented SBS version as suggested
by the standard. The support for PEC is re-evaluated when the
battery is hotplugged into the system, since there might be
systems supporting batteries from different SBS generations.

Reviewed-by: Emil Velikov <emil.velikov@collabora.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>