ARM: PXA: fix up decompressor code

The earlier removal of two boards caused a build regression,
fix it by removing the extraneous '||'.

Reported-by: kernel test robot <lkp@intel.com>
Fixes: 28f74201 ("ARM: pxa: remove Intel Imote2 and Stargate 2 boards")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>