drm/bridge: tfp410: fix memleak in get_modes()

We don't free the edid blob allocated by the call to drm_get_edid(),
causing a memleak. Fix this by calling kfree(edid) at the end of the
get_modes().

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190610135739.6077-1-tomi.valkeinen@ti.com