m68k: init_irq_proc depends on CONFIG_PROC_FS

If CONFIG_PROC_FS is not set, I get:

| arch/m68k/kernel/ints.c:433: error: redefinition of 'init_irq_proc'
| include/linux/interrupt.h:438: error: previous definition of 'init_irq_proc' was here

This was introduced by commit 6168a702


("Declare init_irq_proc before we use it."), which replaced the #ifdef
protection of the init_irq_proc() call by a static inline dummy if
CONFIG_PROC_FS is not set.

Make init_irq_proc() depend on CONFIG_PROC_FS to fix this.

Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>