Remove interrupt-controller as a valid property under /chosen in
 the documentation.  There is a consensus that an
 interrupt-controller property does not belong under /chosen.
 /chosen is specifically for dynamic properties set at runtime.
Signed-off-by: NStuart Yoder <stuart.yoder@freescale.com>
Signed-off-by: NPaul Mackerras <paulus@samba.org>