linux-imx

parisc,metag: Implement CONFIG_DEBUG_STACK_USAGE option

On parisc and metag the stack grows upwards, so for those we need to
scan the stack downwards in order to calculate how much stack a process
has used.

Tested on a 64bit parisc kernel.

Signed-off-by: Helge Deller <deller@gmx.de>