wlr_surface: fix argument order consistency
requested to merge gvideo434/wlroots:github/fork/ifreund/surface-accepts-touch-arg-order into master
This swaps the argument order of wlr_surface_accepts_touch() and wlr_surface_accepts_tablet_v2(), putting the wlr_surface argument first as should be the case for functions namespaced with wlr_surface_*.