target/xtensa: fix clang analyzer warnings and gcc12 build errors

target/xtensa: fix clang analyzer warnings and gcc12 build errors

Fix Unused code	Dead assignment at line 657
Fix Memory error Double free at line 2851
Fix Memory error Memory leak at line 2530
Fix error: 'a3' may be used uninitialized at line 758
Fix error: '%04x' directive writing between 4 and 8 bytes
into a region of size 5 at line 2471

Signed-off-by: Erhan Kurubas <erhan.kurubas@espressif.com>
Change-Id: I0382a622bc7c4108a335fd741816577e79240397
Reviewed-on: https://review.openocd.org/c/openocd/+/7137
Tested-by: jenkins
Reviewed-by: Ian Thompson <ianst@cadence.com>
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>