spi: spi-imx: fix sparse warning: add identifier name to function definition

spi: spi-imx: fix sparse warning: add identifier name to function definition

This patch fixes the following and similar sparse warnings by adding
the missing identifier names to the function definitions:

| WARNING: function definition argument 'struct spi_imx_data *' should also have an identifier name
| #68: FILE: drivers/spi/spi-imx.c:68:
| +       int (*prepare_message)(struct spi_imx_data *, struct spi_message *);

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://lore.kernel.org/r/20220502175457.1977983-2-mkl@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>