[CORE] Use unsigned long instead of u32 for vmm_delay APIs

Currently, we use u32 parameters for vmm_delay APIs which means
even on 64bit host we will endup implementing arch_delay_xxxx()
using 32bit registers.

This patch updates all vmm_delay APIs to use unsiged long instead
of u32 so that we can use unsigned long for arch_delay_xxxx(). This
will help us use 64bit registers on 64bit host for implementing
arch_delay_xxxx() functions.

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