irqchip/xtensa-pic: Include header for xtensa_pic_init_legacy()

The declaration for this function is not included, which leads to a harmless warning:

drivers/irqchip/irq-xtensa-pic.c:91:12: error: no previous prototype for 'xtensa_pic_init_legacy' [-Werror=missing-prototypes]

Signed-off-by: Arnd Bergmann <[email protected]>
Reviewed-by: Max Filippov <[email protected]>
Signed-off-by: Marc Zyngier <[email protected]>
Link: https://lore.kernel.org/r/[email protected]

Author: arndb

drivers/irqchip/irq-xtensa-pic.c

@@ -16,6 +16,7 @@
 #include <linux/irqdomain.h>
 #include <linux/irq.h>
 #include <linux/irqchip.h>
+#include <linux/irqchip/xtensa-pic.h>
 #include <linux/of.h>
 
 unsigned int cached_irq_mask;