rt2x00: rt{2500,73}usb.c put back duplicate id

put back 0x050d,0x7050 to rt73usb, same usb_id for two chips:

K7SF5D7050A ver 2xxx is rt2500
K7SF5D7050B ver 3xxx is rt73

<http://en-us-support.belkin.com/app/answers/detail/a_id/297/kw/K7SF5D7050>

Signed-off-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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