spi: mxic: Support per spi-mem operation frequency switches

Every ->exec_op() call correctly configures the spi bus speed to the
maximum allowed frequency for the memory using the constant spi default
parameter. Since we can now have per-operation constraints, let's use
the value that comes from the spi-mem operation structure instead. In
case there is no specific limitation for this operation, the default spi
device value will be given anyway.

The per-operation frequency capability is thus advertised to the spi-mem
core.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Link: https://patch.msgid.link/20241224-winbond-6-11-rc1-quad-support-v2-11-ad218dbc406f@bootlin.com
Signed-off-by: Mark Brown <broonie@kernel.org>

drivers/spi/spi-mxic.c

@@ -522,7 +522,7 @@ static int mxic_spi_mem_exec_op(struct spi_mem *mem,
 	int i, ret;
 	u8 addr[8], cmd[2];
 
-	ret = mxic_spi_set_freq(mxic, mem->spi->max_speed_hz);
+	ret = mxic_spi_set_freq(mxic, op->max_freq);
 	if (ret)
 		return ret;
 
@@ -582,6 +582,7 @@ static const struct spi_controller_mem_caps mxic_spi_mem_caps = {
 	.dtr = true,
 	.ecc = true,
 	.swap16 = true,
+	.per_op_freq = true,
 };
 
 static void mxic_spi_set_cs(struct spi_device *spi, bool lvl)