Impact: Bugfix, avoids kernels which build but panic on boot

Fix a bug in decompress.c : only scanned until the first
non-configured compressor (with disastrous result especially if that
was gzip.)
Signed-off-by: NAlain Knaff <alain@knaff.lu>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>