Modify cert convert script

1. Problem : In format_cert.sh, use hash function to make out_file.
Script : subject_hash function use SHA1 algorithm.
Android : use old hash function(MD5 algoritm).
Therefore, there is some CTS fail occured in test_KeyStore_cacerts.
in test_KeyStore_cacerts test, devices cannot find added certificate's
subject hashed name.

2. Solution : In format_cert.sh, change the hash function
subject_hash -> subject_hash_old

Change-Id: Ic378c5b96d2ee1a47cde4a59d5d3e701d9ef6e68
Signed-off-by: SangJin Cha <sj.cha@lge.com>