rt2x00: change REGISTER_BUSY_COUNT for USB

Because of delays on USB we do not have to iterate so many times on
USB hardware when waiting for H/W register become valid.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

diff --cc drivers/net/wireless/rt2x00/rt2500usb.c
Simple merge

diff --cc drivers/net/wireless/rt2x00/rt2x00.h
Simple merge

diff --cc drivers/net/wireless/rt2x00/rt2x00usb.c
Simple merge

diff --cc drivers/net/wireless/rt2x00/rt73usb.c
Simple merge