ppc64le: adjust qemu minimum memory config
ppc64le: adjust qemu minimum memory config

Currently qemu/ppc64le requires at least 256 MiB of memory.
This temporary fix enforces this limit to overwrite the fixed
default of 128 MiB. In the long run a global config would be preferd.

Signed-off-by: Peter Morjan <964d0cf54dbf76d367f54f543a3db8d083ad8566@de.ibm.com>

gao-feng/runv,laijs/runv,hyperhq/runv,jinfenw/runv,gao-feng/runv,jinfenw/runv,gao-feng/runv,laijs/runv,gnawux/runv,hyperhq/runv,wrouesnel/runv,feiskyer/runv,hyperhq/runv,gnawux/runv,jinfenw/runv,feiskyer/runv,gnawux/runv,bergwolf/runv,bergwolf/runv,bergwolf/runv,wrouesnel/runv,laijs/runv