mmc: mtk-sd: Add condition to enable 'single' burst type

mmc: mtk-sd: Add condition to enable 'single' burst type

This change add a condition for 'single' burst type selection.

Read AXI_LEN field from EMMC50_CFG2(AHB2AXI wrapper) register, if the
value is not 0, it means the HWIP is using AXI as AMBA bus, which do
not support 'single' burst type.

Suggested-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Axe Yang <axe.yang@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20250411054134.31822-1-axe.yang@mediatek.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>