power: qcom-charger: add support to detect parallel charger

Add support to detect presence of parallel charger chip by
requesting a register read via power_supply framework.
If parallel chip is absent then disable parallel charger.

Change-Id: Icfa4a774d344fde4c7d1f4ced772a707be85020d
Signed-off-by: Ashay Jaiswal <ashayj@codeaurora.org>
Signed-off-by: Abhijeet Dharmapurikar <adharmap@codeaurora.org>