arm: convert to generic helpers for IPI function calls

This converts arm to use the new helpers for smp_call_function() and
friends, and adds support for smp_call_function_single().

Fixups and testing done by Catalin Marinas <catalin.marinas@arm.com>

Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

include/asm-arm/smp.h

@@ -101,6 +101,9 @@ extern void platform_cpu_die(unsigned int cpu);
 extern int platform_cpu_kill(unsigned int cpu);
 extern void platform_cpu_enable(unsigned int cpu);
 
+extern void arch_send_call_function_single_ipi(int cpu);
+extern void arch_send_call_function_ipi(cpumask_t mask);
+
 /*
  * Local timer interrupt handling function (can be IPI'ed).
  */