Update license to use SPDX-License-Identifier instead of verbose license
text.

Link: http://lkml.kernel.org/r/87bm60csyl.wl-kuninori.morimoto.gx@renesas.comSigned-off-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Reviewed-by: NSimon Horman <horms+renesas@verge.net.au>
Cc: Rich Felker <dalias@libc.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>