spmi: pmic_arb: add support for hw version 2

Qualcomm PMIC Arbiter version-2 changes from version-1 are:

- Some different register offsets.
- New channel register space, one per PMIC peripheral (ppid).
  All tx traffic uses these channels.
- New observer register space. All rx trafic uses this space.
- Different command format for spmi command registers.

Reviewed-by: Sagar Dharia <sdharia@codeaurora.org>
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>
Tested-by: Ivan T. Ivanov <iivanov@mm-sol.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>