net: ll_temac: Replace bad usage of msleep() with usleep_range()

Use usleep_range() to avoid problems with msleep() actually sleeping
much longer than expected.

Signed-off-by: Esben Haabendal <esben@geanix.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>