scripts: decodecode: remove bashisms
scripts: decodecode: remove bashisms

Remove bashisms to make scripts/decodecode work with other shells.

Signed-off-by: Rabin Vincent <6bd3f43fd5b2b5689bccc97f6d09e3eb28307598@rab.in>
Reviewed-by: WANG Cong <0f114804888b88d50037b04b42e57b858d851b87@gmail.com>
Signed-off-by: Michal Marek <0c835876a532a476f30fdb1f6e963bae6c5a1a04@suse.cz>

TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs