ioapic.h: prevent potential compiler warning

Includes device.h to prevent potential compiler warnings due to use of
'struct device *' in _ioapic_init() declaration.

Change-Id: Iabd97c09385044a3742658f66a79be969b62852a
Work-by: Johan Kruger <johan.kruger@windriver.com>
Signed-off-by: Peter Mitsis <peter.mitsis@windriver.com>

include/drivers/ioapic.h

@@ -62,6 +62,7 @@ SECTION_FUNC(TEXT, _\()\device\()_\()\isr\()_stub)
 	jmp     _IntExit        /* Inform kernel interrupt is done */
 .endm
 #else /* _ASMLANGUAGE */
+#include <device.h>
 int _ioapic_init(struct device *unused);
 void _ioapic_irq_enable(unsigned int irq);
 void _ioapic_irq_disable(unsigned int irq);