power: qpnp-fg-gen4: Fix parallel current summing configuration

Currently, mem_attn interrupt is enabled and parallel current
summing configuration is attempted 1 second later after mem_attn
interrupt fires again. However, with interrupt disabled in lazy
way, this is causing issues with multiple insertion/removal
events. Fix this by marking mem_attn interrupt unlazy which
would help with disabling interrupt immediately so that we don't
have to wait for 1 second in addition. Also, enable and disable
mem_attn interrupt in the same function where parallel summing
configuration is modified so that it is protected by mutex lock
of voter.

Change-Id: I5c91848466c1866880041137c4cf3f46eeab45dc
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>