net: mvneta: fix txq_map in case of txq_number==1

net: mvneta: fix txq_map in case of txq_number==1

If we boot with mvneta.txq_number=1, the txq_map is set incorrectly:
MVNETA_CPU_TXQ_ACCESS(1) refers to TX queue 1, but only TX queue 0 is
initialized. Fix this.

Fixes: 50bf8cb6fc9c ("net: mvneta: Configure XPS support")
Signed-off-by: Klaus Kudielka <klaus.kudielka@gmail.com>
Reviewed-by: Michal Kubiak <michal.kubiak@intel.com>
Link: https://lore.kernel.org/r/20230705053712.3914-1-klaus.kudielka@gmail.com
Signed-off-by: Paolo Abeni <pabeni@redhat.com>