drm/bridge: adv7511: Remove private copy of the EDID

The adv7511 driver keeps a private copy of the EDID in its driver state
struct. But this copy is only used in adv7511_get_modes() where it is also
retrieved, so there is no need to keep this extra copy around.

If a need to access the EDID elsewhere in the driver ever arises the copy
that is stored in the connector can be used. This copy is accessible
through drm_connector_get_edid().

Note, this patch removes the NULL check of the EDID before passing it to
drm_detect_hdmi_monitor(), but that is fine since the function correctly
handles the case where the EDID is NULL.

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Tested-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20170905121018.11477-2-lars@metafoo.de