ASoC: SOF: mediatek: mt8195: remove a redundant comparison of sram

DSP SRAM is not used for audio shared buffer between host and DSP so
TOTAL_SIZE_SHARED_SRAM_FROM_TAIL is zero. Remove the definition and
redundant comparison to fix coverity "unsigned compared against 0".

Signed-off-by: YC Hung <yc.hung@mediatek.com>
Reviewed-by: AngeloGioacchino Del Regno <angeloigoacchino.delregno@collabora.com>
Link: https://lore.kernel.org/r/20221215061046.16934-1-yc.hung@mediatek.com
Signed-off-by: Mark Brown <broonie@kernel.org>