README: update (C) entry

There are tools that automatically extract this information, so better
make it up to date.

Signed-off-by: Wolfgang Denk <wd@denx.de>

README

 #
-# (C) Copyright 2000 - 2011
+# (C) Copyright 2000 - 2012
 # Wolfgang Denk, DENX Software Engineering, wd@denx.de.
 #
 # See file CREDITS for list of people who contributed to this