ARM: rmobile: Enable RPC on Salvator-X, ULCB, Ebisu

ARM: rmobile: Enable RPC on Salvator-X, ULCB, Ebisu

Enable the RPC Hyperflash driver on R8A7795,R8A7796,R8A77965
Salvator-X,ULCB and R8A77990 Ebisu. Note that to make the HF
accessible, mainline ATF is mandatory and must be built with
RCAR_RPC_HYPERFLASH_LOCKED=0 . Note that this is intended for
development and testing convenience only and must be disabled
in deployment for platform security reasons.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>