qpnp-smb2: smb-lib: update reading charge_done property

Instead of setting charge_done property from smb-lib when
handling chg_state_change interrupt, move it to a separate
function which reads the hardware register directly and
updates it. Since this doesn't require a set_property callback,
remove it.

Change-Id: I1005b135f5e16111257902413ef2b44c09cb1cfc
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>