spi: Fix the error description in the ptp_sts_word_post comment

Based on the comment information, the description within the
`ptp_sts_word_post` section should be changed to "See @ptp_sts_word_pre".

Signed-off-by: Dewei Meng <mengdewei@cqsoftware.com.cn>
Link: https://patch.msgid.link/20260421025808.6572-1-mengdewei@cqsoftware.com.cn
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: Dewei Meng

include/linux/spi/spi.h

@@ -1019,7 +1019,7 @@ struct spi_res {
  *	this value may have changed compared to what was requested, depending
  *	on the available snapshotting resolution (DMA transfer,
  *	@ptp_sts_supported is false, etc).
- * @ptp_sts_word_post: See @ptp_sts_word_post. The two can be equal (meaning
+ * @ptp_sts_word_post: See @ptp_sts_word_pre. The two can be equal (meaning
  *	that a single byte should be snapshotted).
  *	If the core takes care of the timestamp (if @ptp_sts_supported is false
  *	for this controller), it will set @ptp_sts_word_pre to 0, and