drm/i915/hdmi: return -EINVAL instead of -1

Avoid using the incidental -EPERM.
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Jani Nikula <jani.nikula@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/8acf7ffe9222d23c7f47dbd95ff1f737221ff72c.1633000838.git.jani.nikula@intel.com

drivers/gpu/drm/i915/display/intel_hdmi.c

@@ -1703,7 +1703,7 @@ int intel_hdmi_hdcp2_read_msg(struct intel_digital_port *dig_port,
 		drm_dbg_kms(&i915->drm,
 			    "msg_sz(%zd) is more than exp size(%zu)\n",
 			    ret, size);
-		return -1;
+		return -EINVAL;
 	}
 
 	offset = HDCP_2_2_HDMI_REG_RD_MSG_OFFSET;