staging: drm/imx: ipu-dc: add WCLK/WRG opcodes

Add WRG and WCLK opcodes to the display controller microcode,
and allow multi instruction codes.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>