ARM: 6026/1: ARM: Add support for LZMA-compressed kernel images

This patch allows using a kernel image compressed with LZMA on ARM.
Extracting the image is fairly slow, but it might be useful on machines
with a very limited amount of storage, as the size benefit is quite
significant (about 25% smaller with LZMA compared to GZIP)

Tested-by: Martin Michlmayr <tbm@cyrius.com>
Tested-by: Paulius Zaleckas <paulius.zaleckas@gmail.com>
Signed-off-by: Albin Tonnerre <albin.tonnerre@free-electrons.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>