llama : fix Gemma-2 Query scaling factors (#8473)
* 9B - query_pre_attn_scalar = 256 not 224
See https://github.com/google/gemma_pytorch/commit/03e657582d17cb5a8617ebf333c1c16f3694670e
Gemma 9b should use 256 and not 224 (self.config.hidden_size // self.config.num_attention_heads)
* llama : fix Gemma-2 Query scaling factor
ggml-ci
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Co-authored-by: Daniel Han <danielhanchen@gmail.com>