sungem: use mdelay instead of udelay where necessary

Some architectures like ARM cannot handle large numbers as
arguments to udelay, so the drivers should use mdelay when
delaying for multiple miliseconds.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: David S. Miller <davem@davemloft.net>