drm/bridge:anx7625: Update HDCP content status

drm/bridge:anx7625: Update HDCP content status

When user enabled HDCP feature, userspace will set HDCP content
to DRM_MODE_CONTENT_PROTECTION_DESIRED. Next, anx7625 will update
HDCP content to DRM_MODE_CONTENT_PROTECTION_ENABLED if down stream
support HDCP feature.

As anx7625 bridge IC will be power down after call .atomic_disable(),
then all HDCP status will be lost on chip. So we should reestablish
HDCP again in .atomic_enable(), and update hdcp content to DESIRE if
current HDCP content is ENABLE in .atomic_disable().

v4:
 - Change HDCP content value to DESIRED if HDCP status is ENABLE in bridge
interface .atomic_enable().

v3:
 - Move hdcp content value checking from bridge interface
.atomic_check() to .atomic_enable()

v2:
 - Add more details in commit message

Signed-off-by: Xin Ji <xji@analogixsemi.com>
Tested-by: Pin-yen Lin <treapking@chromium.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20241219070330.224996-1-xji@analogixsemi.com
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20241219070330.224996-1-xji@analogixsemi.com