ARM: shmobile: bockw: add SMSC ethernet support

This patch adds SMSC ethernet support on Bock-W

Bock-W SMSC needs FPGA settings which enables interrupt.
This patch does it on bockw_init() function.
As notes for future, this FPGA settings should be updated,
since this FPGA is using cascaded interrupt.
Current code is assuming that this FPGA interrupt user is only SMSC.

Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Acked-by: Magnus Damm <damm@opensource.se>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>