egl/dri2: fix image loaderPrivate type mixup

egl/dri2: fix image loaderPrivate type mixup

The first callback which uses an image's loaderPrivate data was recently
added. Prior to this, dri2_create_image_khr_texture had been setting the
unused loaderPrivate field on the image it creates. This caused a
pointer type mixup in platform_android when it started using the new
callback. Fix this by no longer unnecessarily setting loaderPrivate in
dri2_create_image_khr_texture.

Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/4010
Fixes: a2fb87eea6d ("egl/android: implement image cleanup callback")
Reviewed-by: Tapani Pälli <tapani.palli@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/8211>