iio: adc: ad7944: fix backported MODULE_IMPORT_NS

Fix compile error due to backported MODULE_IMPORT_NS(). The 6.6 kernel
expects the argument to this to not be quoted while newer kernels
expect it to be quoted.

When we backported commit cbc986c ("iio: adc: ad7944: add support
for SPI offload") we missed adapting this difference.

Signed-off-by: David Lechner <dlechner@baylibre.com>

Author: dlech

drivers/iio/adc/ad7944.c

@@ -901,4 +901,4 @@ module_spi_driver(ad7944_driver);
 MODULE_AUTHOR("David Lechner <dlechner@baylibre.com>");
 MODULE_DESCRIPTION("Analog Devices AD7944 PulSAR ADC family driver");
 MODULE_LICENSE("GPL");
-MODULE_IMPORT_NS("IIO_DMAENGINE_BUFFER");
+MODULE_IMPORT_NS(IIO_DMAENGINE_BUFFER);