flash: nand: move in include file the declaration of 'nand_devices'

The pointer nand_devices is used in two file.

Move the extern prototype in code.h

Detected through 'sparse' tool.

Change-Id: I7237359fd1a008770a624725cd0b3d8632b4166e
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7674
Tested-by: jenkins

src/flash/nand/core.h

@@ -179,6 +179,7 @@ enum oob_formats {
 	NAND_OOB_YAFFS2 = 0x100,/* when writing, use YAFFS2 OOB layout */
 };
 
+extern struct nand_device *nand_devices;
 
 struct nand_device *get_nand_device_by_num(int num);
 

src/flash/nand/tcl.c

@@ -17,9 +17,6 @@
 #include "fileio.h"
 #include <target/target.h>
 
-/* to be removed */
-extern struct nand_device *nand_devices;
-
 COMMAND_HANDLER(handle_nand_list_command)
 {
 	struct nand_device *p;