qlge: Turn on RX header split based on platform.

Using 4-byte aligned headers is problematic for some architectures.
Since qlge uses 4-byte aligned rx buffers we split headers for these
architectures into a separate buffer and then recopy to align on 2-byte boundary.

Signed-off-by: Ron Mercer <ron.mercer@qlogic.com>
Signed-off-by: David S. Miller <davem@davemloft.net>