ISDN: eicon: Remove driver

I started looking at the history of this driver, and last time the
maintainer was active on the mailing list was when discussing how to
remove it. This was in 2012:

https://lore.kernel.org/lkml/4F4DE175.30002@melware.de/

It looks to me like this has in practice been an orphan for quite a while.
It's throwing warnings about stack size in a function that is in dire
need of refactoring, and it's probably a case of "it's time to call it".

Cc: Armin Schindler <mac@melware.de>
Cc: Karsten Keil <isdn@linux-pingi.de>
Signed-off-by: Olof Johansson <olof@lixom.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

MAINTAINERS

@@ -7843,13 +7843,6 @@ F:	include/linux/isdn/
 F:	include/uapi/linux/isdn.h
 F:	include/uapi/linux/isdn/
 
-ISDN SUBSYSTEM (Eicon active card driver)
-M:	Armin Schindler <mac@melware.de>
-L:	isdn4linux@listserv.isdn4linux.de (subscribers-only)
-W:	http://www.melware.de
-S:	Maintained
-F:	drivers/isdn/hardware/eicon/
-
 IT87 HARDWARE MONITORING DRIVER
 M:	Jean Delvare <jdelvare@suse.com>
 L:	linux-hwmon@vger.kernel.org

drivers/isdn/hardware/Kconfig

@@ -5,5 +5,3 @@ comment "CAPI hardware drivers"
 
 source "drivers/isdn/hardware/avm/Kconfig"
 
-source "drivers/isdn/hardware/eicon/Kconfig"
-

drivers/isdn/hardware/Makefile

@@ -3,5 +3,4 @@
 # Object files in subdirectories
 
 obj-$(CONFIG_CAPI_AVM)		+= avm/
-obj-$(CONFIG_CAPI_EICON)	+= eicon/
 obj-$(CONFIG_MISDN)		+= mISDN/