board/keymile/kmp204x/Makefile: Convert to SPDX tag

Signed-off-by: Tom Rini <trini@ti.com>

board/keymile/kmp204x/Makefile

@@ -5,20 +5,7 @@
 # See file CREDITS for list of people who contributed to this
 # project.
 #
-# This program is free software; you can redistribute it and/or
-# modify it under the terms of the GNU General Public License as
-# published by the Free Software Foundation; either version 2 of
-# the License, or (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, write to the Free Software
-# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
-# MA 02111-1307 USA
+# SPDX-License-Identifier:	GPL-2.0+
 #
 
 ifneq ($(OBJTREE),$(SRCTREE))