power: qpnp-fg: add battery profile loading support

The battery profile for the PMI8994 fuel gauge peripheral
is represented as a 128 byte long binary blob which
is specified in the batterydata devicetree file for
a given battery.

Upon probe the devicetree data is parsed and written
into the corresponding SRAM offset using a delayed
workqueue.

If no such property is present in the referenced battery
data file, the default OTP profiles will be used by the
fuel gauge and may introduce accuracy issues.

Change-Id: I2605d69265908f0c06d5b47c1dfe87e94c743380
Signed-off-by: David Keitel <dkeitel@codeaurora.org>