* bsp: nxp/mcx/mcxn: SPI: Added missing bracket and re-format code.
The closing bracket is missing from SPI6 struct.
Introduced since commit fc1cfd6d3627ba8460d514e7913bd307e8b1d567 .
Use standard rt_spi_device->cs_pin instead of user_data pointer.
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Signed-off-by: Yilin Sun <imi415@imi.moe>