bootctrl: fixed OOB read in BootControl

Fixed OOB read in BootControl::isSlotMarkedSuccessful() by checking
if "in_slot" is negative

Flag: EXEMPT bugfix
Test: tested on Husky device
Bug: 353516777
Change-Id: I634c32a8c12403008fe5a724bc447f82931ae9c5
Signed-off-by: bgkim <bgkim@google.com>
1 file changed