target/armv8: Add ARM target name on halt status

target/armv8: Add ARM target name on halt status

The CPU target name is added to the HALT status message so the user
can see which target halted at the designated program counter.

Tested on an Ampere eMAG8180 and Quicksilver silicon

Change-Id: I51e6f21296c85a822df28c5b7c4068e8ff66f29e
Signed-off-by: Kevin Burke <kevinb@os.amperecomputing.com>
Signed-off-by: Daniel Goehring <dgoehrin@os.amperecomputing.com>
Reviewed-on: http://openocd.zylin.com/5571
Tested-by: jenkins
Reviewed-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>