[EMULATORS] Avoid direct use of arch_cpu_to_xxxx() APIs

Generally, we prefer use of core APIs wherever possible
instead of directly using arch_xxx() APIs.

On similar lines, we replace use of arch_cpu_to_xxxx() APIs
with vmm_cpu_to_xxxx() APIs.

Signed-off-by: Anup Patel <anup@brainfault.org>