The first member of struct tcan4x5x_map_buf is the struct tcan4x5x_buf_cmd,
which has a size of 4 bytes. It's followed by an array of u8. The compiler
places the array directly after the struct tcan4x5x_buf_cmd.

This patch removes the not needed attribute __packed from the struct
tcan4x5x_map_buf.
Suggested-by: Jakub Kicinski <kuba@kernel.org>
Link: https://lore.kernel.org/r/20210113203955.912916-1-mkl@pengutronix.deSigned-off-by: Marc Kleine-Budde <mkl@pengutronix.de>