spi: spi-imx: Fix casting warnings

spi: spi-imx: Fix casting warnings

Sparse warnings:

drivers/spi/spi-imx.c:410:19: warning: cast to restricted __be32
drivers/spi/spi-imx.c:410:19: warning: cast to restricted __be32
drivers/spi/spi-imx.c:410:19: warning: cast to restricted __be32
drivers/spi/spi-imx.c:410:19: warning: cast to restricted __be32
drivers/spi/spi-imx.c:410:19: warning: cast to restricted __be32
drivers/spi/spi-imx.c:410:19: warning: cast to restricted __be32
drivers/spi/spi-imx.c:439:21: warning: incorrect type in assignment (different base types)
drivers/spi/spi-imx.c:439:21:    expected unsigned int [addressable] [usertype] val
drivers/spi/spi-imx.c:439:21:    got restricted __be32 [usertype]

Signed-off-by: Hardevsinh Palaniya <hardevsinh.palaniya@siliconsignals.io>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20241008055644.4900-3-hardevsinh.palaniya@siliconsignals.io
Signed-off-by: Mark Brown <broonie@kernel.org>