ARM: simplify early machine init hooks

Rather than storing each machine init hook separately, store a
pointer to the machine description record and dereference this
instead.  This pointer is only available while the init sections
are present, which is not a problem as we only use it from init
code.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/include/asm/mach/irq.h

@@ -17,8 +17,6 @@ struct seq_file;
 /*
  * This is internal.  Do not use it.
  */
-extern unsigned int arch_nr_irqs;
-extern void (*init_arch_irq)(void);
 extern void init_FIQ(void);
 extern int show_fiq_list(struct seq_file *, void *);