spi: spi-mt65xx: Add support for MT6991 Dimensity 9400 SPI IPM

Add support for the SPI IPM controller found in the MediaTek
Dimensity 9400 (MT6991) SoC. As a note, this is the same SPI
IPM Controller IP found on the MT8196 Kompanio counterpart.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Link: https://patch.msgid.link/20250611110747.458090-2-angelogioacchino.delregno@collabora.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: AngeloGioacchino Del Regno

drivers/spi/spi-mt65xx.c

@@ -220,6 +220,14 @@ static const struct mtk_spi_compatible mt6893_compat = {
 	.no_need_unprepare = true,
 };
 
+static const struct mtk_spi_compatible mt6991_compat = {
+	.need_pad_sel = true,
+	.must_tx = true,
+	.enhance_timing = true,
+	.dma_ext = true,
+	.ipm_design = true,
+};
+
 /*
  * A piece of default chip info unless the platform
  * supplies it.
@@ -245,6 +253,9 @@ static const struct of_device_id mtk_spi_of_match[] = {
 	{ .compatible = "mediatek,mt6765-spi",
 		.data = (void *)&mt6765_compat,
 	},
+	{ .compatible = "mediatek,mt6991-spi",
+		.data = (void *)&mt6991_compat,
+	},
 	{ .compatible = "mediatek,mt7622-spi",
 		.data = (void *)&mt7622_compat,
 	},