net: macb: Remove CONFIG_PM ifdef because of compilation warning

Fix compilation warning:
drivers/net/ethernet/cadence/macb.c:2415:12: warning: 'macb_suspend'
defined but not used [-Wunused-function]
 static int macb_suspend(struct device *dev)
drivers/net/ethernet/cadence/macb.c:2432:12: warning: 'macb_resume'
defined but not used [-Wunused-function]
 static int macb_resume(struct device *dev)

when CONFIG_PM=y, CONFIG_PM_SLEEP=n are used.

Signed-off-by: Michal Simek <michal.simek@xilinx.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>