spmi-pmic-arb: Add support for spmi-arb channels

Add support for spmi-arb channel I/O protection scheme.
This scheme allows access in per-channel resolution
and each PMIC peripheral has its own channel.

Change-Id: I2c1b8c9fd0c15f18b30513ff10d340c72ba1c2a6
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>
Signed-off-by: Alok Chauhan <alokc@codeaurora.org>
Signed-off-by: Kiran Gunda <kgunda@codeaurora.org>