drm/bridge: dw_hdmi: support i2c extended read mode

"I2C Master Interface Extended Read Mode" implements a segment
pointer-based read operation using the Special Register configuration.

This patch fix https://patchwork.kernel.org/patch/7098101/

 mentioned
"The current implementation does not support "I2C Master Interface
Extended Read Mode" to read data addressed by non-zero segment
pointer, this means that if EDID has more than 1 extension blocks,
EDID reading operation won't succeed"

With this patch, dw-hdmi can read EDID data with 1/2/4 blocks.

Signed-off-by: Nickey Yang <nickey.yang@rock-chips.com>
Reviewed-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Vladimir Zapolskiy <vladimir_zapolskiy@mentor.com>
Signed-off-by: Archit Taneja <architt@codeaurora.org>
Link: http://patchwork.freedesktop.org/patch/msgid/1489978651-16647-1-git-send-email-nickey.yang@rock-chips.com