usb: Tidy up the usb_start flag

This should be declared in a header file so that type-checking works
correctly.

Add a single declaration to usb.h and remove the others.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Marek Vasut <marex@denx.de>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
diff --git a/cmd/usb.c b/cmd/usb.c
index 73addb0..6193728 100644
--- a/cmd/usb.c
+++ b/cmd/usb.c
@@ -620,7 +620,6 @@
 {
 	struct usb_device *udev = NULL;
 	int i;
-	extern char usb_started;
 
 	if (argc < 2)
 		return CMD_RET_USAGE;
diff --git a/common/usb.c b/common/usb.c
index ae9253d..836506d 100644
--- a/common/usb.c
+++ b/common/usb.c
@@ -43,7 +43,7 @@
 #define USB_BUFSIZ	512
 
 static int asynch_allowed;
-char usb_started; /* flag for the started/stopped USB status */
+bool usb_started; /* flag for the started/stopped USB status */
 
 #if !CONFIG_IS_ENABLED(DM_USB)
 static struct usb_device usb_dev[USB_MAX_DEVICE];
diff --git a/drivers/usb/host/usb-uclass.c b/drivers/usb/host/usb-uclass.c
index 28f7ca9..02c0138 100644
--- a/drivers/usb/host/usb-uclass.c
+++ b/drivers/usb/host/usb-uclass.c
@@ -18,7 +18,6 @@
 #include <dm/lists.h>
 #include <dm/uclass-internal.h>
 
-extern bool usb_started; /* flag for the started/stopped USB status */
 static bool asynch_allowed;
 
 struct usb_uclass_priv {
diff --git a/include/usb.h b/include/usb.h
index 80cb846..42b001c 100644
--- a/include/usb.h
+++ b/include/usb.h
@@ -11,12 +11,15 @@
 #ifndef _USB_H_
 #define _USB_H_
 
+#include <stdbool.h>
 #include <fdtdec.h>
 #include <usb_defs.h>
 #include <linux/usb/ch9.h>
 #include <asm/cache.h>
 #include <part.h>
 
+extern bool usb_started; /* flag for the started/stopped USB status */
+
 /*
  * The EHCI spec says that we must align to at least 32 bytes.  However,
  * some platforms require larger alignment.
diff --git a/test/boot/bootdev.c b/test/boot/bootdev.c
index 8cf3f30..606bf4f 100644
--- a/test/boot/bootdev.c
+++ b/test/boot/bootdev.c
@@ -19,9 +19,9 @@
 
 /* Allow reseting the USB-started flag */
 #if defined(CONFIG_USB_HOST) || defined(CONFIG_USB_GADGET)
-extern char usb_started;
+extern bool usb_started;
 #else
-char usb_started;
+#include <usb.h>
 #endif
 
 /* Check 'bootdev list' command */
diff --git a/test/dm/blk.c b/test/dm/blk.c
index 0aa04c6..446c442 100644
--- a/test/dm/blk.c
+++ b/test/dm/blk.c
@@ -16,9 +16,6 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-/* Allow resetting the USB-started flag */
-extern char usb_started;
-
 /* Test that block devices can be created */
 static int dm_test_blk_base(struct unit_test_state *uts)
 {