x11-drivers/xorgxrdp-devel: Fix build with pkg 2.1.0

Fix suggested by bapt.

While here, reformat Makefile with portfmt, and pet portclippy.

PR: 285815
Reported by: Anton Saietskii
Sponsored by: Cybertrust Japan

(cherry picked from commit cfb71f4ea6c6825b49f28e7f0401a5bc2e0fe0a0)