drivers/net/lance.c: fix sparse warnings: fix signedness

drivers/net/lance.c: fix sparse warnings: fix signedness

Impact: Besides from fixing the signedness issue remove some
whitespace to obey to the 80 character limit.

Fix this sparse warnings:
  drivers/net/lance.c:399:19: warning: incorrect type in assignment (different signedness)
  drivers/net/lance.c:654:29: warning: incorrect type in argument 2 (different signedness)

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