irqdomain: Include internals.h for function prototypes

irq_domain_debugfs_init() is defined in irqdomain.c, but the
declaration is in a header that is not included here:

kernel/irq/irqdomain.c:1965:13: error: no previous prototype for 'irq_domain_debugfs_init' [-Werror=missing-prototypes]
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Marc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20230516200432.554240-1-arnd@kernel.org

kernel/irq/irqdomain.c

@@ -1915,6 +1915,8 @@ static void irq_domain_check_hierarchy(struct irq_domain *domain)
 #endif	/* CONFIG_IRQ_DOMAIN_HIERARCHY */
 
 #ifdef CONFIG_GENERIC_IRQ_DEBUGFS
+#include "internals.h"
+
 static struct dentry *domain_dir;
 
 static void