QNNPACK: GNU aarch64 assembler does not support 4s on neon mov

Unlike clang, GNU assembler does not support 4s type on neon mov and gives these errors:

> 8x8-dq-aarch64-neon.S: Assembler messages:
> 8x8-dq-aarch64-neon.S:657:
> Error: operand mismatch -- `mov V8.4s,V9.4s'
> Info:    did you mean this?
> Info:            mov v8.8b, v9.8b
> Info:    other valid variant(s):
> Info:            mov v8.16b, v9.16b

Changing to 16b fixes the issue.