cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer

cadence: cdns-mhdp8546*: Change drm_connector from structure to pointer

Now that we have dropped the legacy code which became redundant with
introduction of DRM_BRIDGE_ATTACH_NO_CONNECTOR
usecase in driver,we can cleanly switch to drm_connector pointer
instead of structure.

Rename the connector_ptr member variable to connector for clarity and
consistency. The driver was using both connector and connector_ptr members,
but connector_ptr was the only one actually used throughout the code.
This change removes the unused connector struct member and renames
connector_ptr to connector for better readability.

This is purely a code cleanup change with no functional impact. All
references to connector_ptr are updated to use the renamed connector
variable throughout the driver.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>
Signed-off-by: Jayesh Choudhary <j-choudhary@ti.com>
Signed-off-by: Harikrishna Shenoy <h-shenoy@ti.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
Link: https://patch.msgid.link/20251209120332.3559893-6-h-shenoy@ti.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>