Remove drivers/net/auto_irq.c.

No more users of the autoirq_xxx() API existed, so this file is not
only unused, it isn't even listed in any makefiles.

drivers/net/auto_irq.c

-/* auto_irq.c: Auto-configure IRQ lines for linux. */
-/*
-    Written 1994 by Donald Becker.
-
-    The author may be reached as becker@scyld.com
-
-    This code is a general-purpose IRQ line detector for devices with
-    jumpered IRQ lines.  If you can make the device raise an IRQ (and
-    that IRQ line isn't already being used), these routines will tell
-    you what IRQ line it's using -- perfect for those oh-so-cool boot-time
-    device probes!
-
-    To use this, first call autoirq_setup(timeout). TIMEOUT is how many
-    'jiffies' (1/100 sec.) to detect other devices that have active IRQ lines,
-    and can usually be zero at boot.  'autoirq_setup()' returns the bit
-    vector of nominally-available IRQ lines (lines may be physically in-use,
-    but not yet registered to a device).
-    Next, set up your device to trigger an interrupt.
-    Finally call autoirq_report(TIMEOUT) to find out which IRQ line was
-    most recently active.  The TIMEOUT should usually be zero, but may
-    be set to the number of jiffies to wait for a slow device to raise an IRQ.
-
-    The idea of using the setup timeout to filter out bogus IRQs came from
-    the serial driver.
-*/
-
-
-#ifdef version
-static const char *version=
-"auto_irq.c:v1.11 Donald Becker (becker@scyld.com)";
-#endif
-
-#include <linux/module.h>
-#include <linux/jiffies.h>
-#include <linux/delay.h>
-#include <asm/bitops.h>
-#include <asm/io.h>
-#include <asm/irq.h>
-#include <linux/netdevice.h>
-
-static unsigned long irqs;
-
-void autoirq_setup(int waittime)
-{
-	irqs = probe_irq_on();
-}
-
-#define BUSY_LOOP_UNTIL(j) while ((long)(jiffies-(j)) < 0) ;
-int autoirq_report(int waittime)
-{
-	unsigned long delay = jiffies + waittime;
-	BUSY_LOOP_UNTIL(delay)
-	return probe_irq_off(irqs);
-}
-
-EXPORT_SYMBOL(autoirq_setup);
-EXPORT_SYMBOL(autoirq_report);
-
-
-/*
- * Local variables:
- *  compile-command: "gcc -DKERNEL -Wall -O6 -fomit-frame-pointer -I/usr/src/linux/net/tcp -c auto_irq.c"
- *  version-control: t
- *  kept-new-versions: 5
- *  c-indent-level: 4
- *  tab-width: 4
- * End:
- */