extract-vmlinux: Output used decompression method

When extract-vmlinux succeeds, it doesn't output which decompression method
was found at which offset. Adding this additional output in check_vmlinux()
helps troubleshooting and reverse-engineering images.

The last check_vmlinux() call was also quoted to accept spaces.

Signed-off-by: Maxime Thiebaut <maxime+kernel@thiebaut.dev>
Reviewed-by: Nicolas Schier <nsc@kernel.org>
Link: https://lore.kernel.org/r/X6OQ4pHdpreJtlTnf0tFEb4Uxz8T8gFv_7Yw6tpBK4ZBgHYjJr_URwUwCVynpkb-H8Yjk7DdBF01zY-sfqu_7N5trZQfcd6s_4PtdGlHtlA=@thiebaut.dev


Signed-off-by: Nathan Chancellor <nathan@kernel.org>