Add stub regulator devices for the SMPS, LDO, and BOB regulators
found on the PMICs used on tuna boards to allow the regulator
clients to vote on them.
Change-Id: I577485fa57f78e71d91fa1e783f20722113d957f
Signed-off-by: Kavya Nunna <quic_knunna@quicinc.com>