graphics/drm-51*-kmod: Add Makefile.version

Projects that live outside of drm-kmod (such as nvidia-drm) will need
to query the version of drm-kmod built against in order to grab the
correct sources. This adds a Makefile.version they can include to do
so.

Differential Revision:	https://reviews.freebsd.org/D39885

graphics/drm-510-kmod/Makefile

@@ -1,8 +1,10 @@
 PORTNAME=	drm-510-kmod
-PORTVERSION=	5.10.163
+PORTVERSION=	${DRM_KMOD_DISTVERSION}
 PORTREVISION=	5
 CATEGORIES=	graphics kld
 
+.include "Makefile.version"
+
 MAINTAINER=	x11@FreeBSD.org
 COMMENT=	DRM drivers modules
 WWW=		https://github.com/freebsd/drm-kmod/
@@ -20,7 +22,7 @@ USES=		kmod uidfix compiler:c++11-lang
 USE_GITHUB=	yes
 GH_ACCOUNT=	freebsd
 GH_PROJECT=	drm-kmod
-GH_TAGNAME=	drm_v5.10.163_4
+GH_TAGNAME=	${DRM_KMOD_GH_TAGNAME}
 
 .include <bsd.port.options.mk>
 

graphics/drm-510-kmod/Makefile.version

@@ -0,0 +1,5 @@
+# drm-kmod common version definition
+#
+# This will be included from consumers such as nvidia-drm
+DRM_KMOD_DISTVERSION=	5.10.163
+DRM_KMOD_GH_TAGNAME=	drm_v5.10.163_4

graphics/drm-515-kmod/Makefile

@@ -1,8 +1,10 @@
 PORTNAME=	drm-515-kmod
-PORTVERSION=	5.15.25
+PORTVERSION=	${DRM_KMOD_DISTVERSION}
 PORTREVISION=	2
 CATEGORIES=	graphics kld
 
+.include "Makefile.version"
+
 MAINTAINER=	x11@FreeBSD.org
 COMMENT=	DRM drivers modules
 WWW=		https://github.com/freebsd/drm-kmod/
@@ -20,7 +22,7 @@ USES=		kmod uidfix compiler:c++11-lang
 USE_GITHUB=	yes
 GH_ACCOUNT=	freebsd
 GH_PROJECT=	drm-kmod
-GH_TAGNAME=	drm_v5.15.25_4
+GH_TAGNAME=	${DRM_KMOD_GH_TAGNAME}
 
 .include <bsd.port.options.mk>
 

graphics/drm-515-kmod/Makefile.version

@@ -0,0 +1,5 @@
+# drm-kmod common version definition
+#
+# This will be included from consumers such as nvidia-drm
+DRM_KMOD_DISTVERSION=	5.15.25
+DRM_KMOD_GH_TAGNAME=	drm_v5.15.25_4