drivers: remove reference to feature-removal-schedule.txt

In commit 9c0ece06 ("Get rid of Documentation/feature-removal.txt"),
Linus removed feature-removal-schedule.txt from Documentation, but there
is still some reference to this file.  So remove them.
Signed-off-by: NTao Ma <boyu.mt@taobao.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

drivers/net/wireless/Kconfig

@@ -156,11 +156,7 @@ config PRISM54
 	---help---
 	  This enables support for FullMAC PCI/Cardbus prism54 devices. This
 	  driver is now deprecated in favor for the SoftMAC driver, p54pci.
-	  p54pci supports FullMAC PCI/Cardbus devices as well. For details on
-	  the scheduled removal of this driver on the kernel see the feature
-	  removal schedule:
-
-	  Documentation/feature-removal-schedule.txt
+	  p54pci supports FullMAC PCI/Cardbus devices as well.
 
 	  For more information refer to the p54 wiki: