net/ena/base: use optimized memcpy version also on Arm

net/ena/base: use optimized memcpy version also on Arm

As the default behavior for arm64 is to alias rte_memcpy as memcpy, ENA
cannot redefine memcpy as rte_memcpy as it would cause nested
declaration.

To make it possible to use optimized memcpy in the ena_com layer on Arm,
the driver now redefines memcpy when it is beneficial:
  * For arm64 only when the flag RTE_ARCH_ARM64_MEMCPY was defined
  * For arm only when the flag RTE_ARCH_ARM_NEON_MEMCPY was defined

Signed-off-by: Michal Krawczyk <mk@semihalf.com>
Reviewed-by: Dawid Gorecki <dgr@semihalf.com>
Reviewed-by: Shai Brandes <shaibran@amazon.com>