The second (end) parameter of mem_malloc_init() denotes the last address
in the malloc region, so we need to subtract one from the current value
to arrive at the correct end. So far this went not noticed, because iomem
doesn't yet display barebox malloc memory region.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>