FP5: Switch to dot product CPU variant

 * FP5:/ $ cat /proc/cpuinfo | grep -m 1 Features
   Features: fp asimd evtstrm aes pmull sha1 sha2 crc32
   atomics fphp asimdhp cpuid asimdrdm lrcpc dcpop asimddp

 * From this, it's evident that our CPU (Qualcomm QCM6490)
   supports all the features of ARMv8.2-DotProd [1].
   Moreover AOSP sets this arch variant in their generic
   cortex-a55 ART target as well [2]. This should unlock
   some optimizations in different code paths.

[1]: https://en.wikichip.org/wiki/arm/armv8#ARMv8_Extensions_and_Processor_Features
[2]: https://android.googlesource.com/device/generic/art/+/refs/heads/master/armv8_cortex_a55/BoardConfig.mk#23

Change-Id: I484bb2bcc181c62e29c04bc6e467e5edea8ac0d8