AArch64: Remove thunderx{,2} memcpy

AArch64: Remove thunderx{,2} memcpy

ThunderX1 and ThunderX2 have been retired for a few years now.
So let's remove the thunderx{,2} specific versions of memcpy.
The performance gain or them was for medium and large sizes
while the generic (aarch64) memcpy will handle just slightly worse.

Signed-off-by: Andrew Pinski <quic_apinski@quicinc.com>
Reviewed-by: Wilco Dijkstra  <Wilco.Dijkstra@arm.com>