target: Use 'bool' data type in target_{step,resume}

target: Use 'bool' data type in target_{step,resume}

While at it, adapt data types of related functions and fix some coding
style issues.

Change-Id: I74db9258fc17b1ee8aa446f35ae722ea7c2f67e6
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/8524
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>
Tested-by: jenkins