ARM: dts: msm: charge the battery at 2A maximum current on PMI8994

The fast charge current for the PMI8994 qpnp-smbcharger is current not
set. This will use the hardware default value, which is 3A. The MTP
batteries are only rated to charge at 2A, so this can damage the
batteries.

Set the fastcharge current property to make sure the batteries are not
damaged during charging.

CRs-Fixed: 713189
Change-Id: I2809e99d29aa8b1dd42edcfb02db62fcafe46c9e
Signed-off-by: Xiaozhe Shi <xiaozhes@codeaurora.org>