cmd: irq: Move do_irqinfo() prototype to a header file

Move do_irqinfo() prototype to a header file, otherwise compiler is not
happy:

  arch/x86/lib/interrupts.c:130:5: warning: no previous prototype for ‘do_irqinfo’ [-Wmissing-prototypes]

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
[trini: Add 'struct cmd_tbl;' to irq_func.h]
Signed-off-by: Tom Rini <trini@konsulko.com>
diff --git a/cmd/irq.c b/cmd/irq.c
index 655aba5..da223b4 100644
--- a/cmd/irq.c
+++ b/cmd/irq.c
@@ -29,9 +29,6 @@
 	"[on, off]"
 );
 
-/* Implemented in $(CPU)/interrupts.c */
-int do_irqinfo(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]);
-
 U_BOOT_CMD(
 	irqinfo,    1,    1,     do_irqinfo,
 	"print information about IRQs",
diff --git a/include/irq_func.h b/include/irq_func.h
index c7c4bab..fb2c540 100644
--- a/include/irq_func.h
+++ b/include/irq_func.h
@@ -10,6 +10,7 @@
 #define __IRQ_FUNC_H
 
 struct pt_regs;
+struct cmd_tbl;
 
 typedef void (interrupt_handler_t)(void *arg);
 
@@ -23,4 +24,7 @@
 void enable_interrupts(void);
 int disable_interrupts(void);
 
+/* Implemented in $(CPU)/interrupts.c */
+int do_irqinfo(struct cmd_tbl *cmdtp, int flag, int argc, char *const argv[]);
+
 #endif