arm64: force CONFIG_SMP=y and remove redundant #ifdefs

Nobody seems to be producing !SMP systems anymore, so this is just
becoming a source of kernel bugs, particularly if people want to use
coherent DMA with non-shared pages.

This patch forces CONFIG_SMP=y for arm64, removing a modest amount of
code in the process.

Signed-off-by: Will Deacon <will.deacon@arm.com>

arch/arm64/kernel/psci.c

@@ -462,8 +462,6 @@ int __init psci_acpi_init(void)
 }
 #endif
 
-#ifdef CONFIG_SMP
-
 static int __init cpu_psci_cpu_init(unsigned int cpu)
 {
 	return 0;
@@ -550,7 +548,6 @@ static int cpu_psci_cpu_kill(unsigned int cpu)
 	return -ETIMEDOUT;
 }
 #endif
-#endif
 
 static int psci_suspend_finisher(unsigned long index)
 {
@@ -585,7 +582,6 @@ const struct cpu_operations cpu_psci_ops = {
 	.cpu_init_idle	= cpu_psci_cpu_init_idle,
 	.cpu_suspend	= cpu_psci_cpu_suspend,
 #endif
-#ifdef CONFIG_SMP
 	.cpu_init	= cpu_psci_cpu_init,
 	.cpu_prepare	= cpu_psci_cpu_prepare,
 	.cpu_boot	= cpu_psci_cpu_boot,
@@ -594,6 +590,5 @@ const struct cpu_operations cpu_psci_ops = {
 	.cpu_die	= cpu_psci_cpu_die,
 	.cpu_kill	= cpu_psci_cpu_kill,
 #endif
-#endif
 };