modetest: remove drmMode{,Plane}Res

There's no point in keeping these around since we already fetch the
complete data set. Add respective count_ variables and greatly simplify
the existing code.

Extra brownie points for:
 - using the inverse order in free_resources()
 - don't memory leak the connector properties
 - free the properties themselves, instead of only the objects

Signed-off-by: Emil Velikov <emil.velikov@collabora.com>
Reviewed-by: Ezequiel Garcia <ezequiel@collabora.com>
Tested-by: Ezequiel Garcia <ezequiel@collabora.com>