spi: txx9: Use transfer speed unconditionally

SPI core validates the transfer speed and defaults to spi->max_speed_hz in
case the transfer speed is not set.

Signed-off-by: Jarkko Nikula <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

drivers/spi/spi-txx9.c

···
 		u32 data;
 		unsigned int len = t->len;
 		unsigned int wsize;
-		u32 speed_hz = t->speed_hz ? : spi->max_speed_hz;
+		u32 speed_hz = t->speed_hz;
 		u8 bits_per_word = t->bits_per_word;
 
 		wsize = bits_per_word >> 3; /* in bytes */