[Android] Removes CPU architecture number from CPU helper.

This was '7' on all ARMv7 devices but was 'AArch64' on the Nexus 9.
Trying to cast to integer was causing a crash. We don't even use this so may as well as wipe it.
Also adds Nvidia to the CPU implementers list.
Merge pull request #1615 from Sonicadvance1/fix_cpu_helper

[Android] Removes CPU architecture number from CPU helper.