Remove au1x00_uart from feature-removal-schedule.txt.

The driver has been removed a while ago already.
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

Documentation/feature-removal-schedule.txt

@@ -132,16 +132,6 @@ Who:	NeilBrown <neilb@suse.de>
 
 ---------------------------
 
-What:	au1x00_uart driver
-When:	January 2006
-Why:	The 8250 serial driver now has the ability to deal with the differences
-	between the standard 8250 family of UARTs and their slightly strange
-	brother on Alchemy SOCs.  The loss of features is not considered an
-	issue.
-Who:	Ralf Baechle <ralf@linux-mips.org>
-
----------------------------
-
 What:   eepro100 network driver
 When:   January 2007
 Why:    replaced by the e100 driver