sh: dma: Make PVR2 DMA configurable.

With arch/sh/drivers/dma/ always being built, the Dreamcast DMA engines
are being unconditionally built in, regardless of whether the DMA API is
enabled or not. This is a regression from previous behaviour, but there
is not much advantage in building them all in unconditionally regardless.
Add a new config option to make it optional, and update the only user of
it to reflect that.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>
diff --git a/arch/sh/drivers/dma/Makefile b/arch/sh/drivers/dma/Makefile
index ab956ad..cff52cb 100644
--- a/arch/sh/drivers/dma/Makefile
+++ b/arch/sh/drivers/dma/Makefile
@@ -4,5 +4,6 @@
 
 obj-$(CONFIG_SH_DMA_API)	+= dma-api.o dma-sysfs.o
 obj-$(CONFIG_SH_DMA)		+= dma-sh.o
-obj-$(CONFIG_SH_DREAMCAST)	+= dma-pvr2.o dma-g2.o
+obj-$(CONFIG_SH_DREAMCAST)	+= dma-g2.o
+obj-$(CONFIG_PVR2_DMA)		+= dma-pvr2.o
 obj-$(CONFIG_SH_DMABRG)		+= dmabrg.o