Use correct register name after it has beed changed
in commit 11ee500bff ("target/armv7m: Rename xPSR to xpsr")
Change-Id: I3648848f4b47af2d20d60c3e0ecef78f75f6d605
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/7473
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>