net: stmmac: perserve TX and RX coalesce value during XDP setup

net: stmmac: perserve TX and RX coalesce value during XDP setup

When XDP program is loaded, it is desirable that the previous TX and RX
coalesce values are not re-inited to its default value. This prevents
unnecessary re-configurig the coalesce values that were working fine
before.

Fixes: ac746c8520d9 ("net: stmmac: enhance XDP ZC driver level switching performance")
Signed-off-by: Ong Boon Leong <boon.leong.ong@intel.com>
Tested-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/20211124114019.3949125-1-boon.leong.ong@intel.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>