spi: Merge spi_controller.{slave,target}_abort()

Mixing SPI slave/target handlers and SPI slave/target controllers using
legacy and modern naming does not work well: there are now two different
callbacks for aborting a slave/target operation, of which only one is
populated, while spi_{slave,target}_abort() check and use only one,
which may be the unpopulated one.

Fix this by merging the slave/target abort callbacks into a single
callback using a union, like is already done for the slave/target flags.

Fixes: b8d3b056 ("spi: introduce new helpers with using modern naming")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/809c82d54b85dd87ef7ee69fc93016085be85cec.1667555967.git.geert+renesas@glider.beSigned-off-by: Mark Brown <broonie@kernel.org>

include/linux/spi/spi.h

@@ -655,8 +655,10 @@ struct spi_controller {
 			       struct spi_message *message);
 	int (*unprepare_message)(struct spi_controller *ctlr,
 				 struct spi_message *message);
-	int (*slave_abort)(struct spi_controller *ctlr);
-	int (*target_abort)(struct spi_controller *ctlr);
+	union {
+		int (*slave_abort)(struct spi_controller *ctlr);
+		int (*target_abort)(struct spi_controller *ctlr);
+	};
 
 	/*
 	 * These hooks are for drivers that use a generic implementation