spi: spi-fsl-dspi: Fix a resource leak in an error handling path

In the Linux kernel, the following vulnerability has been resolved:

spi: spi-fsl-dspi: Fix a resource leak in an error handling path

'dspi_request_dma()' should be undone by a 'dspi_release_dma()' call in the

error handling path of the probe function, as already done in the remove

function