[PATCH] zd1211rw: fix filter for PSPOLL frames

While filling the control set the driver tests for a PSPOLL frame.
But it tested only the subtype of the packet. The full type needs
to be tested to identify those packets reliably.

[dsd@gentoo.org: backport to mainline]
Signed-off-by: Ulrich Kunitz <kune@deine-taler.de>
Signed-off-by: Daniel Drake <dsd@gentoo.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>