spi: spi-mtk-nor: add axi_s clock for mt8186

MT8186 needs axi_s clock for DMA feature.

Signed-off-by: Guochun Mao <guochun.mao@mediatek.com>
Signed-off-by: Zhen Zhang <zhen.zhang@mediatek.com>
Acked-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20220118142820.2729-5-guochun.mao@mediatek.com


Signed-off-by: Mark Brown <broonie@kernel.org>