[PATCH] pcnet32: set_ringparam implementation

This patch implements the set_ringparam(), one of the ethtool operations,
which allows changing tx/rx ring sizes via ethtool.

- Changed memery allocation of tx/rx ring from static to dynamic
- Implemented set_ringparam()
- Tested on i386 and ppc64

Signed-off-by: Hubert WS Lin <wslin@tw.ibm.com>
Signed-off-by: Jay Vosburgh <fubar@us.ibm.com>
Cc: Jeff Garzik <jgarzik@pobox.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Jeff Garzik <jgarzik@pobox.com>