p54: fix tx feedback status flag check
p54: fix tx feedback status flag check

Michael reported that p54* never really entered power
save mode, even tough it was enabled.

It turned out that upon a power save mode change the
firmware will set a special flag onto the last outgoing
frame tx status (which in this case is almost always the
designated PSM nullfunc frame). This flag confused the
driver; It erroneously reported transmission failures
to the stack, which then generated the next nullfunc.
and so on...

Cc: <4fbacc2fa0ffdbb11bf1ad6925b886ebd08dd15f@kernel.org>
Reported-by: Michael Buesch <77666125932addc6fc525b281b518fd8fd2203d8@bu3sch.de>
Tested-by: Michael Buesch <77666125932addc6fc525b281b518fd8fd2203d8@bu3sch.de>
Signed-off-by: Christian Lamparter <2b86d4915b352c348b09e5d907edf5d041a1585c@googlemail.com>
Signed-off-by: John W. Linville <2a53bac7a5d324865ef46ec4c38b2c0fba1456b4@tuxdriver.com>

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