pldm: pldm-scripts: replace readonly with local The array is defined as "readonly" inside a loop. However Bash strictly forbids redefining or modifying a readonly variable once it has been set, resulting in the fatal error. Tested: After fix, the script won't exit due to below error: /usr/bin/pldm_update_fw.sh: line 132: DELAYS: readonly variable Google-Bug-Id: 443118245 Change-Id: I12482601147a56d82ce78cdabbe49816fef50c2e Signed-off-by: Jinliang Wang <jinliangw@google.com>