Redeclaration of 'should_continue' is hidding external variable

Redeclaration of variable 'should_continue' in the inner loop is hiding value of external variable 'should_continue'.

We have doubts this is the intended behaviour. It seems 'should_continue' is used to keep track of whether exit the outer loop. Apparently this change was introduced in d62ffc17 (net_device: Refactor vrings).