net: devlink: region: Pass the region ops to the snapshot function

Pass the region to be snapshotted to the function performing the
snapshot. This allows one function to operate on numerous regions.

v4:
Add missing kerneldoc for ICE

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>