powerpc/boot: fix boot on systems with uncompressed kernel image

[Michael Ellerman]

On Wed, 2016-12-10 at 19:00:43 UTC, Heiner Kallweit wrote:
> This commit broke boot on systems with an uncompressed kernel image,
> namely systems using a cuImage. On such systems the compressed boot
> image (boot wrapper, uncompressed kernel image, ..) is decompressed
> by u-boot already, therefore the boot wrapper code sees an
> uncompressed kernel image.
> 
> The old decompression code silently assumed an uncompressed kernel
> image if it found no valid gzip signature, whilst the new code
> bailed out in this case.
> 
> Fix this by re-introducing such a fallback if no valid compressed
> image is found.
> 
> Fixes: 1b7898ee276b ("Use the pre-boot decompression API")
> Signed-off-by: Heiner Kallweit <hkallweit1 at gmail.com>

Applied to powerpc fixes, thanks.

https://git.kernel.org/powerpc/c/65bc3ece84ef6340cbd80eec10ab9b

cheers