power: smb5: show charger temp only when USB or DC is present

Currently, a wild value from HW is assigned to charger temp property
in battery psy if USB is not present. However, a valid temperature is
required when DC is present and nondeterministic temp is not desired
when neither input is present.

Fix it by showing it only when USB or DC charger is inserted.

Change-Id: I14c001972b13907efaac5c43b90de3358f34591e
Signed-off-by: Harry Yang <harryy@codeaurora.org>