net: ethernet: cortina: Count dropped frames as NAPI work

In the Linux kernel, the following vulnerability has been resolved: net: ethernet: cortina: Count dropped frames as NAPI work The RX loop only consumes budget when it successfully delivers a frame. Error paths keep consuming descriptors without reducing the budget, so a stream of bad frames can process the entire receive ring in one poll. Move the budget accounting to a common end-of-frame path. This counts each completed frame as NAPI work whether it was delivered or dropped, matching the behavior of the vendor driver.