tools: mkimage: add support for Vybrid image format

This format can be flashed directly at address 0 of
the NAND FLASH, as it contains all necessary headers.

Signed-off-by: Albert ARIBAUD (3ADEV) <albert.aribaud@3adev.fr>

include/image.h

@@ -278,6 +278,7 @@ enum {
 	IH_TYPE_ZYNQIMAGE,		/* Xilinx Zynq Boot Image */
 	IH_TYPE_ZYNQMPIMAGE,		/* Xilinx ZynqMP Boot Image */
 	IH_TYPE_FPGA,			/* FPGA Image */
+	IH_TYPE_VYBRIDIMAGE,	/* VYBRID .vyb Image */
 
 	IH_TYPE_COUNT,			/* Number of image types */
 };