Altera TSE: Fix Panic in probe routine when phy probe fails

This patch addresses a fault in the error recovery path of the probe
routine where the netdev structure was not being unregistered properly
leading to a panic only when the phy probe failed.

Abbreviated panic stack seen is as follows:

(free_netdev+0xXX) from (altera_tse_probe+0xXX)
(altera_tse_probe+0xXX) from (platform_drv_probe+0xXX)
(platform_drv_probe+0xXX) from (driver_probe_device+0xXX)
(driver_probe_device+0xXX) from (__driver_attach+0xXX)
(__driver_attach+0xXX) from (bus_for_each_dev+0xXX)
(bus_for_each_dev+0xXX) from (driver_attach+0xXX)
(driver_attach+0xXX) from (bus_add_driver+0xXX)
(bus_add_driver+0xXX) from (driver_register+0xXX)
(driver_register+0xXX) from (__platform_driver_register+0xXX)
(__platform_driver_register+0xXX) from (altera_tse_driver_init+0xXX)
(altera_tse_driver_init+0xXX) from (do_one_initcall+0xXX)
(do_one_initcall+0xXX) from (kernel_init_freeable+0xXX)
(kernel_init_freeable+0xXX) from (kernel_init+0xXX)
(kernel_init+0xXX) from (ret_from_fork+0xXX)

Signed-off-by: Vince Bridgers <vbridgers2013@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>