net: stmmac: est: Drop frames causing HLBS error

net: stmmac: est: Drop frames causing HLBS error

Drop those frames causing Head-of-Line Blocking due to Scheduling
(HLBS) error to avoid HLBS interrupt flooding and netdev watchdog
timeouts due to blocked packets. Tx queues can be configured to drop
those blocked packets by setting Drop Frames causing Scheduling Error
(DFBS) bit of EST_CONTROL register.

Also, add per queue HLBS drop count.

Signed-off-by: Rohan G Thomas <rohan.g.thomas@altera.com>
Reviewed-by: Matthew Gerlach <matthew.gerlach@altera.com>
Reviewed-by: Furong Xu <0x1207@gmail.com>
Link: https://patch.msgid.link/20250925-hlbs_2-v3-1-3b39472776c2@altera.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>