spi: Remove repeated struct declaration

struct spi_transfer is declared twice. One is declared at 24th line.
The blew one is not needed though. Remove the duplicate.

Signed-off-by: Wan Jiabing <wanjiabing@vivo.com>
Link: https://lore.kernel.org/r/20210401065904.994121-1-wanjiabing@vivo.com


Signed-off-by: Mark Brown <broonie@kernel.org>