First, the former implementation has only considered the pure numerical
variant of the -m argument. Yet, qemu also allows specifying the amount
of memory by `-m 1G`, `-m size=1G` and more.
Second, the default amount of memory for BOARD=pc was 512M (800M in case of okl4).
Since the depot_autopilot.run also required at least 768M on all
platforms it seems reasonable to take 800M as a default value for BOARD=pc and
thereby remove the special treatment of okl4.
genodelabs/genode#4311
c0c2ed2bf5