lib: fdt: Allow enabling both LZO and GZIP DT compression

Allow enabling both LZO and GZIP DT compression in SPL and fix a
bug where if the GZIP decompression failed, the LZO decompression
would not even be attempted.

Signed-off-by: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Nobuhiro Iwamatsu <iwamatsu@nigauri.org>
Cc: Simon Glass <sjg@chromium.org>
Cc: Tom Rini <trini@konsulko.com>