omap3_spi: introduce CONFIG_OMAP3_SPI_D0_D1_SWAPPED

D0/D1 Swapped or not is a board property, not anything specific to
the am33xx SoC, so add a custom define for it.

At the same time correct the bit handling for the swapped mode
(DPE0 should be cleared and SI/DPE1 set).

Signed-off-by: Peter Korsgaard <peter.korsgaard@barco.com>

drivers/spi/omap3_spi.c

@@ -173,14 +173,13 @@ int spi_claim_bus(struct spi_slave *slave)
 	/* standard 4-wire master mode:	SCK, MOSI/out, MISO/in, nCS
 	 * REVISIT: this controller could support SPI_3WIRE mode.
 	 */
-#ifdef CONFIG_AM33XX
+#ifdef CONFIG_OMAP3_SPI_D0_D1_SWAPPED
 	/*
-	 * The reference design on AM33xx has D0 and D1 wired up opposite
-	 * of how it has been done on previous platforms.  We assume that
-	 * custom hardware will also follow this convention.
+	 * Some boards have D0 wired as MOSI / D1 as MISO instead of
+	 * The normal D0 as MISO / D1 as MOSI.
 	 */
-	conf &= OMAP3_MCSPI_CHCONF_DPE0;
-	conf |= ~(OMAP3_MCSPI_CHCONF_IS|OMAP3_MCSPI_CHCONF_DPE1);
+	conf &= ~OMAP3_MCSPI_CHCONF_DPE0;
+	conf |= OMAP3_MCSPI_CHCONF_IS|OMAP3_MCSPI_CHCONF_DPE1;
 #else
 	conf &= ~(OMAP3_MCSPI_CHCONF_IS|OMAP3_MCSPI_CHCONF_DPE1);
 	conf |= OMAP3_MCSPI_CHCONF_DPE0;