mmc: tmio: name 0xd8 as CTL_DMA_ENABLE

This reflects at least the current usage of this register
and I think it improves the readability of the code ever so slightly.

Cc: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Cc: Magnus Damm <magnus.damm@gmail.com>
Signed-off-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Chris Ball <cjb@laptop.org>

drivers/mmc/host/tmio_mmc_dma.c

@@ -26,7 +26,7 @@ static void tmio_mmc_enable_dma(struct tmio_mmc_host *host, bool enable)
 {
 #if defined(CONFIG_SUPERH) || defined(CONFIG_ARCH_SHMOBILE)
 	/* Switch DMA mode on or off - SuperH specific? */
-	writew(enable ? 2 : 0, host->ctl + (0xd8 << host->bus_shift));
+	writew(enable ? 2 : 0, host->ctl + (CTL_DMA_ENABLE << host->bus_shift));
 #endif
 }
 

include/linux/mmc/tmio.h

@@ -30,6 +30,7 @@
 #define CTL_TRANSACTION_CTL 0x34
 #define CTL_SDIO_STATUS 0x36
 #define CTL_SDIO_IRQ_MASK 0x38
+#define CTL_DMA_ENABLE 0xd8
 #define CTL_RESET_SD 0xe0
 #define CTL_SDIO_REGS 0x100
 #define CTL_CLK_AND_WAIT_CTL 0x138