power: qpnp-fg: improve IMA error checking mechanism

Currently, we check for IMA errors only after the transaction is
initiated. Check for it even before the transactions begin from
hardware status. This way it will be guaranteed that the hardware
is in a right state.

Also, while checking for errors, it would be more appropriate to
check for the error bits in exception status than just the error
status as the former has more information including the latter.

Change-Id: I8826546640313dc73e55aff22f236c4fe18599ad
Signed-off-by: Subbaraman Narayanamurthy <subbaram@codeaurora.org>