Don't compare pointers with 0, use NULL when needed.
Don't assign pointer to 0, use NULL.
Don't pass 0 ad pointer argument, pass NULL.
Detected through 'sparse' tool.
Change-Id: I3f867cb9c0903f6e396311e7b3970ee5fb3a4231
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/7597
Tested-by: jenkins