parisc: switch to gzip-compressed vmlinuz kernel

The latest PA-RISC Boot Loader (palo) allows loading of gzip compressed
vmlinuz kernels. So let's now switch to build a vmlinuz file when we
build a palo boot image.

PALO version 1.9 (or higher) is required for this which is available at
git://git.kernel.org/pub/scm/linux/kernel/git/deller/palo.git



Signed-off-by: Helge Deller <deller@gmx.de>
Cc: <stable@vger.kernel.org> # 3.10