libcamera: v4l2_subdevice: Implement ENUM_FRAME_SIZES

Implement format and size enumeration methods to list all the available
subdevice image resolutions and formats.

Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Jacopo Mondi <jacopo@jmondi.org>

src/libcamera/include/geometry.h

@@ -17,6 +17,18 @@ struct Rectangle {
 	unsigned int h;
 };
 
+struct SizeRange {
+	SizeRange(unsigned int minW, unsigned int minH,
+		  unsigned int maxW, unsigned int maxH)
+		: minWidth(minW), minHeight(minH), maxWidth(maxW),
+		  maxHeight(maxH) {}
+
+	unsigned int minWidth;
+	unsigned int minHeight;
+	unsigned int maxWidth;
+	unsigned int maxHeight;
+};
+
 } /* namespace libcamera */
 
 #endif /* __LIBCAMERA_GEOMETRY_H__ */