Return after removing sample LTK device

Return directly after calling bta_dm_remove_device to
prevent from accessing the invalid security record (p_dev_rec).

Test: Hardcode to test bond with sample key
Tag: #security
Bug: 162497143
Change-Id: Iaa59f3c415dd8066849fd70912fdb83f890229d7
Merged-In: Iaa59f3c415dd8066849fd70912fdb83f890229d7