Most of ST-Link commands return an error code, but this is almost
never checked.
Check for the error code for every command that returns it.
Change-Id: Ifc4e32f8c73196de23700ba0989bfdfe0f5b46e3
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Reviewed-on: http://openocd.zylin.com/4825
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>