octeontx2-pf: Refactor schedular queue alloc/free calls

1. Upon txschq free request, the transmit schedular config in hardware
is not getting reset. This patch adds necessary changes to do the same.

2. Current implementation calls txschq alloc during interface
initialization and in response handler updates the default txschq array.
This creates a problem for htb offload where txsch alloc will be called
for every tc class. This patch addresses the issue by reading txschq
response in mbox caller function instead in the response handler.

3. Current otx2_txschq_stop routine tries to free all txschq nodes
allocated to the interface. This creates a problem for htb offload.
This patch introduces the otx2_txschq_free_one to free txschq in a
given level.

Signed-off-by: Hariprasad Kelam <hkelam@marvell.com>
Signed-off-by: Naveen Mamindlapalli <naveenm@marvell.com>
Signed-off-by: Sunil Kovvuri Goutham <sgoutham@marvell.com>
Signed-off-by: David S. Miller <davem@davemloft.net>