jme: Safer MAC processor reset sequence

Adding control to clk_rx, and makes the control of clk_{rx|tx|tcp}
with safer sequence.
This sequence is provided by JMicron.

Signed-off-by: Guo-Fu Tseng <cooldavid@cooldavid.org>
Signed-off-by: David S. Miller <davem@davemloft.net>