Revert "releasetools: Fix error text in ota_from_target_files"

This reverts commit 48afd1a7b35b943e434cfaa41a5b24bae1bc43e8.
Revert "ota_from_target_files: remove duplicate setting of recovery_img"

This reverts commit 1750acc37b2e2cc301fa34fcb1b8d555ad40df58.
bring support to 4.8 :D

Change-Id: Ibd47a212a15a78e07bcd7a0586f6f63a7ab48792
Signed-off-by: klozz <xxx.reptar.rawrr.xxx@gmail.com>