power: qpnp-fg: support setting sense_type

Use the sense_type module parameter to allow users to change the sensing
channel of the fuel gauge to external or internal. Also, add the
qcom,sense-type property to allow users to configure the sense
channel at compile time.

Change-Id: I74e4234a82ff80150216523ffbdecb26e86d4f0a
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>