cteonxt2-pf: Fix backpressure config for multiple PFC priorities to work simultaneously

cteonxt2-pf: Fix backpressure config for multiple PFC priorities to work simultaneously

MAC (CGX or RPM) asserts backpressure at TL3 or TL2 node of the egress
hierarchical scheduler tree depending on link level config done. If
there are multiple PFC priorities enabled at a time and for all such
flows to backoff, each priority will have to assert backpressure at
different TL3/TL2 scheduler nodes and these flows will need to submit
egress pkts to these nodes.

Current PFC configuration has an issue where in only one backpressure
scheduler node is being allocated which is resulting in only one PFC
priority to work. This patch fixes this issue.

Fixes: 99c969a83d82 ("octeontx2-pf: Add egress PFC support")
Signed-off-by: Suman Ghosh <sumang@marvell.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://lore.kernel.org/r/20230824081032.436432-4-sumang@marvell.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>