davinci_emac: Add Carrier Link OK check in Davinci RX Handler

This patch adds an additional check in the Davinci EMAC RX Handler,
which tests the __LINK_STATE_NOCARRIER flag along with the
__LINK_STATE_START flag as part EMAC shutting down procedure.

This avoids
WARNING: at drivers/net/davinci_emac.c:1040 emac_rx_handler+0xf8/0x120()
during rtcwake used to suspend the target for a specified duration.

Signed-off-by: Hegde, Vinay <vinay.hegde@ti.com>
Acked-by: Cyril Chemparathy <cyril@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>