drm/bridge: it6505: add AUX operation for HDCP KSV list read

HDCP KSV list readback can choose to use AUX FIFO or
general data register.
For some DisplayPort devices, the KSV list must be read
in 5 byte boundaries.
The original AUX read command does not support these devices.

The AUX command operation control register "REG_AUX_CMD_REQ" uses b[3:0]
as AUX operacion control, and b[7:4] are status bits and read only.
To change KSV read operation uses "CMD_AUX_NATIVE_READ" from using
the data registers to using AUX FIFO.
The extended command "CMD_AUX_GET_KSV_LIST" is added as
"CMD_AUX_NATIVE_READ" with the 0x10 flag which selects AUX FIFO mode.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Hermes Wu <hermes.wu@ite.com.tw>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241230-v7-upstream-v7-3-e0fdd4844703@ite.corp-partner.google.com