zram: add copyright

(cherry pick from commit 7bfb3de8a1b3bebc2dc68d381efe27448c0584c5)

Add my copyright to the zram source code which I maintain.

Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Bug: 24810447
Change-Id: Ie6353ef599481e2681bac62f85a2673d6f51b271