spmi-pmic-arb: block access to unmapped peripherals

pmic-arb v2 spmi controller features mappping from ppid to channel
number in its register space. This map can be used by the driver to
block access to ppids which are not mapped.

CRs-fixed: 815806
Change-Id: I441ae17a4fb3c6312c79a7c8dd848d7c3e03aee6
Signed-off-by: Gilad Avidov <gavidov@codeaurora.org>