Staging: rt2870: rtusb_probe() should be in section __devinit

$ make CONFIG_DEBUG_SECTION_MISMATCH=y
WARNING: drivers/staging/rt2870/rt2870sta.o(.text+0x2f4c5): Section
mismatch in reference from the function rtusb_probe() to the function .devinit.text:rt2870_probe()
The function rtusb_probe() references
the function __devinit rt2870_probe().
This is often because rtusb_probe lacks a __devinit
annotation or the annotation of rt2870_probe is wrong.

Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>