spi: spi-fsl-lpspi: fsl_lpspi_setup_transfer(): remove useless spi_transfer NULL...

spi: spi-fsl-lpspi: fsl_lpspi_setup_transfer(): remove useless spi_transfer NULL pointer check

fsl_lpspi_setup_transfer() is either called via:

| fsl_lpspi_prepare_message()
| -> fsl_lpspi_setup_transfer()

or

| -> spi_transfer_one_message()
| -> controller->transfer_one == fsl_lpspi_transfer_one()
| -> fsl_lpspi_setup_transfer()

The first call path already has a spi_transfer NULL pointer check, the
second one explicitly iterates over all spi_transfer of the spi_message.

Simplify the code by removing the useless NULL pointer check.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
Link: https://patch.msgid.link/20260319-spi-fsl-lpspi-cleanups-v2-7-02b56c5d44a8@pengutronix.de
Signed-off-by: Mark Brown <broonie@kernel.org>