DM9000: Use msleep() instead of udelay()

We can use sleeping functions when reading and writing the
PHY registers, so let us sleep instead of busy waiting for
the PHY.

Note, this also fixes a bug reading the PHY where only 100uS
was being used instead of 150uS

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Jeff Garzik <jeff@garzik.org>