s390/net: reduce inlining

Clean up the inline cruft in s390 net drivers. Many of the inlined
functions had only one caller anyway.

Suggested-by: Joe Perches <joe@perches.com>
Signed-off-by: Julian Wiedmann <jwi@linux.vnet.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>