Prevent integer issues in ID3::Iterator::findFrame

Integer overflows could occur a few places within findFrame. These can lead to
out-of-bounds reads and potentially infinite loops. Ensure that arithmetic does
not wrap around to prevent these behaviors.

Bug: 23285192
Change-Id: I72a61df7d5719d1d3f2bd0b37fba86f0f4bbedee
Ticket: CYNGNOS-985