octeontx2-af: Don't reset previous pfc config

Current implementation is such that driver first resets the
existing PFC config before applying new pfc configuration.
This creates a problem like once PF or VFs requests PFC config
previous pfc config by other PFVfs is getting reset.

This patch fixes the problem by removing unnecessary resetting
of PFC config. Also configure Pause quanta value to smaller as
current value is too high.

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