target: consolidate existing target/algo common_magic

target: consolidate existing target/algo common_magic

Unify common_magic type to unsigned int
Move common_magic to be the first member of the struct
Add unsigned specifier to xxx_COMMON_MAGIC #defines

Change-Id: If961d33232698529514ba3720e04418baf6dc6fe
Signed-off-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-on: https://review.openocd.org/c/openocd/+/6996
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>