drm/tests: hdmi: Switch to 'void *' type for EDID data

drm/tests: hdmi: Switch to 'void *' type for EDID data

Replace 'const char *' with 'const void *' type for current_edid member
in struct drm_atomic_helper_connector_hdmi_priv, as well as for the edid
parameter of set_connector_edid() function.

Suggested-by: Jani Nikula <jani.nikula@linux.intel.com>
Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/r/20250527-hdmi-conn-yuv-v5-8-74c9c4a8ac0c@collabora.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>