The default environment buffer is an unsigned char array and thus
may be unaligned. Some decompression algorithms expect the buffer
to be sufficiently aligned for u32 accesses. We make this sure by
copying the default env to a temporary buffer. Instead of doing this
just add a __aligned(4) to the default environment.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>