kmscube: Fix incorrect modifier check in create_framebuffer function

When importing an egl image from a linux dma buf fd, we need to pass the proper image attributes to eglCreateImageKHR. The modifier check here should not ignore DRM_FORMAT_MOD_LINEAR when setting EGL_DMA_BUF_PLANE0_MODIFIER_LO/HI_EXT else the ordering of samples within a plane will be incorrect, resulting in incorrect/garbled pixels being presented.