ucc_geth: Remove UGETH_MAGIC_PACKET Kconfig symbol and code

This patch removes currently unused UGETH_MAGIC_PACKET Kconfig symbol
and code, i.e. magic_packet_detection_{enable,disable} functions.

The two functions each contain just two steps that we'll place into
suspend/resume code path under CONFIG_PM.

Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Signed-off-by: David S. Miller <davem@davemloft.net>