Merge branch 'cpsw-common-res-usage'

Ivan Khoronzhuk says:

====================
net: ethernet: ti: cpsw: correct common res usage

This series is intended to remove unneeded redundancies connected with
common resource usage function.

Since v1:
- changed name to cpsw_get_usage_count()
- added comments to open/closw for cpsw_get_usage_count()
- added patch:
  net: ethernet: ti: cpsw: clarify ethtool ops changing num of descs

Based on net-next/master
====================

Reviewed-by: Grygorii Strashko <[email protected]>
Signed-off-by: David S. Miller <[email protected]>