pKVM provides a workaround for A0 hardware issue. Signal to tests that
an A0 device should not be run without it by enabling it in /misc on
first boot. We only do this on debug builds.
Bug: 266183966
Test: flash, boot, reboot to bootloader, check 'fastboot oem pkvm'
Change-Id: I9465cf816c65943cba6e04b1d939b0bb5af4395d