drm/bridge: anx7625: add HDCP support

This patch provides HDCP setting interface for userspace to dynamic
enable/disable HDCP function.

Reported-by: kernel test robot <[email protected]>
Reviewed-by: Robert Foss <[email protected]>
Signed-off-by: Xin Ji <[email protected]>
Signed-off-by: Robert Foss <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

Author: Xin-ANX