Unlock only once for HardwareBuffer::lock_planes()

AHardwareBuffer_unlock() unlocks all the plane addresses together. Fix
the per-plane lock guards to unlock only once by reference counting.

Bug: 371874777
Test: atest libnativewindow_rs-internal_test
Flag: EXEMPT bugfix
Change-Id: I8d4c7bce9c3913f78858cf430beb717b205cf95e