arch/arm: add XZ compression support

Conflicts:

	arch/arm/boot/compressed/Makefile
	arch/arm/boot/compressed/decompress.c

Conflicts:
	arch/arm/boot/compressed/Makefile
	arch/arm/boot/compressed/decompress.c

Change-Id: I9167739142d3ba7428067987a09cf0e3bb1fe158
update .gitignore

Signed-off-by: Dennis Rassmann <showp1984@gmail.com>