net: fec: init complete variable in early to avoid kernel dump

Software clear the MDIO interrupt before MDIO bus access, but
MAC still generate MDIO interrupt. The issue only happen on
imx6slx chip.

CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.17.0-rc1-00399-g0bcad17 #315
Backtrace:
[<800121fc>] (dump_backtrace) from [<800124e0>] (show_stack+0x18/0x1c)
 r6:8096e534 r5:8096e534 r4:00000000 r3:00000000
[<800124c8>] (show_stack) from [<806a4c60>] (dump_stack+0x8c/0xa4)
[<806a4bd4>] (dump_stack) from [<80060ab8>] (__lock_acquire+0x1814/0x1c40)
 r6:be078000 r5:be074000 r4:be03f6e4 r3:be078000
[<8005f2a4>] (__lock_acquire) from [<800616e0>] (lock_acquire+0x70/0x84)
 r10:809ada33 r9:be010600 r8:00000096 r7:00000001 r6:be074000 r5:00000000
 r4:60000193
[<80061670>] (lock_acquire) from [<806abb20>] (_raw_spin_lock_irqsave+0x40/0x54)
 r7:00000000 r6:8005a3f8 r5:00000193 r4:be03f6d4
[<806abae0>] (_raw_spin_lock_irqsave) from [<8005a3f8>] (complete+0x1c/0x4c)
 r6:80950904 r5:be03f6d0 r4:be03f6d4
[<8005a3dc>] (complete) from [<8041b4c0>] (fec_enet_interrupt+0x128/0x164)
 r6:80950904 r5:00800000 r4:be03f000 r3:00000000
[<8041b398>] (fec_enet_interrupt) from [<8006aeac>] (handle_irq_event_percpu+0x38/0x13c)
 r6:00000000 r5:be01065c r4:be399e00 r3:8041b398
[<8006ae74>] (handle_irq_event_percpu) from [<8006aff4>] (handle_irq_event+0x44/0x64)
 r10:be03f000 r9:80989fe0 r8:00000000 r7:00000096 r6:be399e00 r5:be01065c
 r4:be010600
[<8006afb0>] (handle_irq_event) from [<8006e3e8>] (handle_fasteoi_irq+0xc8/0x1bc)
 r6:8096e764 r5:be01065c r4:be010600 r3:00000000
[<8006e320>] (handle_fasteoi_irq) from [<8006a63c>] (generic_handle_irq+0x30/0x44)
 r6:be074010 r5:80945e4c r4:00000096 r3:8006e320
[<8006a60c>] (generic_handle_irq) from [<8000f218>] (handle_IRQ+0x54/0xbc)
 r4:80950d74 r3:00000180
[<8000f1c4>] (handle_IRQ) from [<800086cc>] (gic_handle_irq+0x30/0x68)
 r8:be3ab478 r7:c080e100 r6:be075bd8 r5:80950eec r4:c080e10c r3:000000a0
[<8000869c>] (gic_handle_irq) from [<80013064>] (__irq_svc+0x44/0x5c)

Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: Frank Li <Frank.Li@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/fec_main.c

@@ -3066,6 +3066,7 @@ fec_probe(struct platform_device *pdev)
 			goto failed_irq;
 	}
 
+	init_completion(&fep->mdio_done);
 	ret = fec_enet_mii_init(pdev);
 	if (ret)
 		goto failed_mii_init;