ARM: 7001/2: Wire up support for the XZ decompressor

Wire up support for the XZ decompressor

Change-Id: Iba5c1d548a9bf7f5e54326865c427e6c13d81e37
Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>