dm9000: during init reset phy only for dm9000b

Some of the changes introduced in commit 6741f40 (DM9000B: driver
initialization upgrade) break functionality on DM9000A
(error message during NFS boot: "dm9000 dm9000.0: eth0: link down")

Since the changes were meant to serve only DM9000B, make them
dependent on the chip type.

Cc: David S. Miller <davem@davemloft.net>
Cc: Jingoo Han <jg1.han@samsung.com>
Cc: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Nikita Kiryanov <nikita@compulab.co.il>
Signed-off-by: Igor Grinberg <grinberg@compulab.co.il>
Signed-off-by: David S. Miller <davem@davemloft.net>