spi: imx: Don't expect DMA for i.MX{25,35,50,51,53} cspi devices

While in commit 2dd33f9c ("spi: imx: support DMA for imx35") it was
claimed that DMA works on i.MX25, i.MX31 and i.MX35 the respective
device trees don't add DMA channels. The Reference manuals of i.MX31 and
i.MX25 also don't mention the CSPI core being DMA capable. (I didn't
check the others.)

Since commit e267a5b3

 ("spi: spi-imx: Use dev_err_probe for failed
DMA channel requests") this results in an error message

	spi_imx 43fa4000.spi: error -ENODEV: can't get the TX DMA channel!

during boot. However that isn't fatal and the driver gets loaded just
fine, just without using DMA.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://patch.msgid.link/20240508095610.2146640-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>