ARM: prima2: build reset code standalone

The prima2 platform code currently depends on the rstc
implementation and that in turn depends on the reset
controller framework. This removes the platform dependency
by letting the driver access arm_pm_restart directly
to turn the driver into a standalone entity, and also
removes the dependency on the reset controller framework
by using "if (IS_ENABLED(CONFIG_RESET_CONTROLLER))". This
will cause all code that is used for the reset controller
to be dropped by the compiler if the framework is disabled.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-prima2/common.h

@@ -23,7 +23,6 @@ extern void sirfsoc_secondary_startup(void);
 extern void sirfsoc_cpu_die(unsigned int cpu);
 
 extern void __init sirfsoc_of_irq_init(void);
-extern void sirfsoc_restart(enum reboot_mode, const char *);
 extern asmlinkage void __exception_irq_entry sirfsoc_handle_irq(struct pt_regs *regs);
 
 #ifndef CONFIG_DEBUG_LL