drm/bridge: tda998x: Return NULL instead of 0 in tda998x_edid_read()

drm/bridge: tda998x: Return NULL instead of 0 in tda998x_edid_read()

tda998x_edid_read() returns a const struct drm_edid pointer, but when
tda998x_edid_delay_wait() fails (process killed while waiting for the
HPD timeout), the integer literal 0 is returned instead of NULL,
triggering a sparse warning: "Using plain integer as NULL pointer"

Replace 0 with NULL to fix the sparse warning.

Fixes: c76a8be4feec ("drm/bridge: tda998x: Add support for DRM_BRIDGE_ATTACH_NO_CONNECTOR")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202604172257.Imo6GOH9-lkp@intel.com/
Signed-off-by: Kory Maincent (TI) <kory.maincent@bootlin.com>
Reviewed-by: Luca Ceresoli <luca.ceresoli@bootlin.com>
Link: https://patch.msgid.link/20260417155446.1068893-1-kory.maincent@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>