headers: Drop two #included headers from <linux/interrupt.h>

It seems that <linux/interrupt.h> does not need <linux/linkage.h>
nor <linux/preempt.h>.  8 kernels builds are successful without
these 2 headers (allmodconfig, allyesconfig, allnoconfig, and
tinyconfig on both i386 and x86_64).

<linux/interrupt.h> is #included 3875 times in 4.16-rc1, so this
reduces #include processing of these 2 files by a total of 7750 times.

Since I only tested x86 builds, this needs to be tested on other
$ARCHes as well.

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-arch@vger.kernel.org
Link: http://lkml.kernel.org/r/b24b9ec8-4970-65f5-759a-911d4ba2fcf0@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>

include/linux/interrupt.h

@@ -4,9 +4,7 @@
 #define _LINUX_INTERRUPT_H
 
 #include <linux/kernel.h>
-#include <linux/linkage.h>
 #include <linux/bitops.h>
-#include <linux/preempt.h>
 #include <linux/cpumask.h>
 #include <linux/irqreturn.h>
 #include <linux/irqnr.h>