rt2x00: rt2800usb: fix status register reread logic
rt2x00: rt2800usb: fix status register reread logic

Another good catch from Jakub Kicinski. This patch fixes my
recent commit: ed61e2b02027935520d1be884fac0b2ffce8379a
"rt2x00: rt2800usb: rework txdone code"

We should reread status register only when nobody else start already
reading status i.e. test_and_set_bit(TX_STATUS_READING, flags) return 0.

Reported-by: Jakub Kicinski <861206be83264dc7c061485a9a09b4656524438c@wp.pl>
Signed-off-by: Stanislaw Gruszka <1542dc81552e668e197a396f69e655c1621c300d@redhat.com>
Acked-by: Gertjan van Wingerde <1a7d4b7fcc67848a7146b426400f699af933a40d@gmail.com>
Signed-off-by: John W. Linville <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas