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