tty/serial: cleanup after ioc*_serial driver removal

Commit 9c860e4 ("tty/serial: remove the ioc3_serial driver") and
commit a017ef1 ("tty/serial: remove the ioc4_serial driver") removed
the ioc{3,4}_serial driver, but missed some files.

Fortunately, ./scripts/get_maintainer.pl --self-test complains:

  warning: no file matches F: drivers/tty/serial/ioc?_serial.c

The driver is gone, so remove the header and maintainer
entry as well.

The serial.rst Documentation might be useful, so we keep it and update
the maintainer entry to the document's actual maintainers.

Signed-off-by: Lukas Bulwahn <[email protected]>
Reviewed-by: Christoph Hellwig <[email protected]>
Signed-off-by: Tony Luck <[email protected]>

Author: bulwahn

MAINTAINERS

@@ -7946,6 +7946,7 @@ L:	[email protected]
 T:	git git://git.kernel.org/pub/scm/linux/kernel/git/aegl/linux.git
 S:	Maintained
 F:	arch/ia64/
+F:	Documentation/ia64/
 
 IBM Power 842 compression accelerator
 M:	Haren Myneni <[email protected]>
@@ -15042,14 +15043,6 @@ M:	Dimitri Sivanich <[email protected]>
 S:	Maintained
 F:	drivers/misc/sgi-gru/
 
-SGI SN-IA64 (Altix) SERIAL CONSOLE DRIVER
-M:	Pat Gefre <[email protected]>
-L:	[email protected]
-S:	Supported
-F:	Documentation/ia64/serial.rst
-F:	drivers/tty/serial/ioc?_serial.c
-F:	include/linux/ioc?.h
-
 SGI XP/XPC/XPNET DRIVER
 M:	Cliff Whickman <[email protected]>
 M:	Robin Holt <[email protected]>