drm/dp_mst: Remove redundant tile property setting

drm_get_edid() already updates the tile property since
commit 2de3a078 ("drm/dp: Set the connector's TILE property even for DP SST connectors")
so no need to update it after calling this function.

Cc: Lyude Paul <lyude@redhat.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210201120145.350258-3-imre.deak@intel.com