eal: add new prefetch write variants

eal: add new prefetch write variants

This commit adds new rte_prefetchX_write() variants, that suggest to the
compiler to use a prefetch instruction with intention to write. As a
compiler builtin, the compiler can choose based on compilation target
what the best implementation for this instruction is.

Three versions are provided, targeting the different levels of cache.

Signed-off-by: Harry van Haaren <harry.van.haaren@intel.com>
Reviewed-by: Jerin Jacob <jerinj@marvell.com>
Reviewed-by: Ruifeng Wang <ruifeng.wang@arm.com>