ui/gtk-egl: blitting partial guest fb to the proper scanout surface

ui/gtk-egl: blitting partial guest fb to the proper scanout surface

eb_fb_blit should be able to blit partial image of guest display (blob res)
in case multiple displays are configured for the guest and they are set as extended-
desktop mode.

v2: egl_fb includes dmabuf info then make egl_fb_blit position and size
    parameters programmed in dmabuf structure (previously position/size
    parameters were given to egl_fb_blit separately)
    (Vivek Kasireddy)

    changed the commit message as there is no interface change to egl_fb_blit

Cc: Gerd Hoffmann <kraxel@redhat.com>
Cc: Vivek Kasireddy <vivek.kasireddy@intel.com>
Signed-off-by: Dongwon Kim <dongwon.kim@intel.com>
Message-Id: <20211104065153.28897-6-dongwon.kim@intel.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>