target/arc: fix build with clang

target/arc: fix build with clang

Commit da41bce3aee9 ("target/arc: introduce breakpoint
functionality") introduces a mismatch between the format string
and one int constant.

Change the format string to match the int constant.

Change-Id: I0d59552205551b90e165c0a2e3fef247ad0c7701
Signed-off-by: Antonio Borneo <borneo.antonio@gmail.com>
Fixes: da41bce3aee9 ("target/arc: introduce breakpoint functionality")
Reviewed-on: http://openocd.zylin.com/5655
Tested-by: jenkins
Reviewed-by: Evgeniy Didin <didin@synopsys.com>
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>