target/cortex_m: enhance multi-core examine logs

target/cortex_m: enhance multi-core examine logs

Giving the example of STM32WL55x the examine log is the following:
  Info : stm32wlx.cpu0: hardware has 6 breakpoints, 4 watchpoints
  Info : stm32wlx.cpu1: hardware has 4 breakpoints, 2 watchpoints

After this change the examine log becomes:
  Info : stm32wlx.cpu0: Cortex-M4 r0p1 processor detected
  Info : stm32wlx.cpu0: target has 6 breakpoints, 4 watchpoints
  Info : stm32wlx.cpu1: Cortex-M0+ r0p1 processor detected
  Info : stm32wlx.cpu1: target has 4 breakpoints, 2 watchpoints

Change-Id: I1873a75eb76f0819342c441129427b38e984f0df
Signed-off-by: Tarek BOCHKATI <tarek.bouchkati@gmail.com>
Reviewed-on: https://review.openocd.org/c/openocd/+/6553
Tested-by: jenkins
Reviewed-by: Tomas Vanek <vanekt@fbl.cz>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>