This board at the moment has no support for PMIC regulators, but
the CCI requires a vproc regulator in order to both stop giving
dtbs_check warnings and to actually probe.
Since vproc is a system-critical regulator and the bootloader
enables it at max voltage, model it (at least temporarily) as
a regulator-fixed and assign it to CCI.
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>