drivers/net/ni65.c: fix sparse warnings: symbol shadows an earlier one

Impact: Remove redundant variable declaration or move them to a more
inner scope.

Fix this sparse warnings:
  drivers/net/ni65.c:900:37: warning: symbol 'p' shadows an earlier one
  drivers/net/ni65.c:874:21: originally declared here
  drivers/net/ni65.c:925:21: warning: symbol 'p' shadows an earlier one
  drivers/net/ni65.c:874:21: originally declared here
  drivers/net/ni65.c:945:29: warning: symbol 'k' shadows an earlier one
  drivers/net/ni65.c:926:15: originally declared here

Signed-off-by: Hannes Eder <hannes@hanneseder.net>
Signed-off-by: David S. Miller <davem@davemloft.net>