Move decompression further down the code flow, so that - where

Move decompression further down the code flow, so that - where
possible - code is decompressed directly to the right place
(instead of copying around, as before).

The downside of this approach is that it's not possible (without API
changes to the decompressors) to put partial segments into bounce
buffers. So if a segment collides with coreboot _and_ is compressed,
it's bounced entirely.
But, as this only brings back the copy we already had before, the new
worst case is better than the average before.

It also fixes handling of compressed segments.

Signed-off-by: Patrick Georgi <patrick.georgi@coresystems.de>
Acked-by: Ronald G. Minnich <rminnich@gmail.com>
git-svn-id: svn://svn.coreboot.org/coreboot/trunk@4207 2b7e53f0-3cfb-0310-b3e9-8179ed1497e1