spdx: The BSD-3-Clause-FreeBSD identifier never was, drop -FreeBSD

There never was a BSD-3-Clause-FreeBSD SPDX identifier. Replace it
with BSD-3-Clause.

Discussed with:		pfg
MFC After:		3 days
Sponsored by:		Netflix

lib/libgeom/geom_getxml.c

@@ -1,5 +1,5 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause-FreeBSD
+ * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2003 Poul-Henning Kamp
  * All rights reserved.

lib/libgeom/geom_stats.c

@@ -1,5 +1,5 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause-FreeBSD
+ * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2003 Poul-Henning Kamp
  * All rights reserved.

lib/libgeom/geom_xml2tree.c

@@ -1,5 +1,5 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause-FreeBSD
+ * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2003 Poul-Henning Kamp
  * All rights reserved.

lib/libgeom/libgeom.h

@@ -1,5 +1,5 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause-FreeBSD
+ * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2003 Poul-Henning Kamp
  * All rights reserved.

sbin/fsck_ffs/ea.c

@@ -1,5 +1,5 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause-FreeBSD
+ * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2002 Poul-Henning Kamp
  * Copyright (c) 2002 Networks Associates Technology, Inc.

usr.sbin/gstat/gstat.c

@@ -1,5 +1,5 @@
 /*-
- * SPDX-License-Identifier: BSD-3-Clause-FreeBSD
+ * SPDX-License-Identifier: BSD-3-Clause
  *
  * Copyright (c) 2003 Poul-Henning Kamp
  * All rights reserved.