x86: delete unneeded declarations of disable_irq() and enable_irq()

These two declarations in arch/x86/include/asm/interrupt.h conflict
with ones in include/linux/compat.h, so x86 boards cannot include
<linux/compat.h>.

The comment /* arch/x86/lib/interrupts.c */ is bogus now, and we do
not see any definitions of disable_irq() and enable_irq() in there.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Simon Glass <sjg@chromium.org>

arch/x86/include/asm/interrupt.h

@@ -16,10 +16,6 @@
 /* arch/x86/cpu/interrupts.c */
 void set_vector(u8 intnum, void *routine);
 
-/* arch/x86/lib/interrupts.c */
-void disable_irq(int irq);
-void enable_irq(int irq);
-
 /* Architecture specific functions */
 void mask_irq(int irq);
 void unmask_irq(int irq);