[CORE] vmm_delay: Call arch_delay_loop() without disabling interrupts

Currently, we were calling arch_delay_loop() with interrupts disabled
to ensure that delay given by arch_delay_loop() is atomic and will not
be preempted by interrupts.

This approach it is not fair in multithreaded system. For example, if
we have a thread executing large soft delay then it will endup doing
arch_delay_loop() for time longer than time slice allotted to it (i.e.
consuming unnecessary more CPU then it should).

To make our soft delay APIs more fairer for multithreaded system, this
patch ensures that we call arch_delay_loop() without disabling interrupts.

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