arm_mem_barebox_image() is used to pick a suitable place where to
put the final image to. This is called from both the PBL uncompression
code and also from the final image. To make it work properly it is
crucial that it's called with the same arguments both times. Currently
it is called with the wrong image size from the PBL uncompression code.
The size passed to arm_mem_barebox_image() has to be the size of the
whole uncompressed image including the BSS segment size. The PBL code
calls it with the compressed image size instead and without the BSS
segment. This patch fixes this by reading the uncompressed image size
from the compressed binary (the uncompressed size is appended to the
end of the compressed binary by our compression wrappers). The size
of the BSS segment is unknown though by the PBL uncompression code,
so we introduce a maximum BSS size which is used instead.

The code before this patch worked by accident because the base address
of the final image was aligned down to a 1MiB boundary. The alignment
was sufficient already to make enough space. This breaks though when
the uncompressed image including BSS becomes bigger than 1MiB while
the compressed image is smaller.

Fixes: 65071bd0: arm: Clarify memory layout calculation

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