ARM: highbank: add missing include

highbank_pm_init() is declared in core.h this is not included in the
file that defines it.

arch/arm/mach-highbank/pm.c:43:13: error: no previous prototype for 'highbank_pm_init'
Acked-by: Andre Przywara <andre.przywara@arm.com>
Link: https://lore.kernel.org/r/20230516153109.514251-4-arnd@kernel.orgSigned-off-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/mach-highbank/pm.c

@@ -12,6 +12,8 @@
 
 #include <uapi/linux/psci.h>
 
+#include "core.h"
+
 #define HIGHBANK_SUSPEND_PARAM \
 	((0 << PSCI_0_2_POWER_STATE_ID_SHIFT) | \
 	 (1 << PSCI_0_2_POWER_STATE_AFFL_SHIFT) | \