power: smb5-lib: update liquid presence detection flow

Currently, in the case where neither device attach nor E-Mark
cable is detected after crude sensor trip, moisture presence is
decided and type-C block is put to sink mode.

However, inserting a legacy cable with the other end floating
can trip the crude sensor which can trigger a false positive
for moisture detection.

Fix this by checking SBU resistance after the crude sensor
trips. Confirm the moisture detection only if the resistance
is low on at least one SBU pin.

Change-Id: Ia43c27eb4026f5ff991cb5073ddb3912e4f4825a
Signed-off-by: Harry Yang <harryy@codeaurora.org>