media: cxd2880-spi: Add optional vcc regulator

This patchset adds an optional VCC regulator to the driver probe function
to make sure power is enabled to the module before starting attaching to
the device.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Acked-by: Yasunari Takiguchi <Yasunari.Takiguchi@sony.com>
Signed-off-by: Sean Young <sean@mess.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>