device property: Introducing enum dev_dma_attr

A device could have one of the following DMA attributes:
    * DMA not supported
    * DMA non-coherent
    * DMA coherent

So, this patch introduces enum dev_dma_attribute. This will be used by
new APIs introduced in later patches.
Signed-off-by: Suravee Suthikulpanit <Suravee.Suthikulpanit@amd.com>
Acked-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Hanjun Guo <hanjun.guo@linaro.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

include/linux/property.h

@@ -27,6 +27,12 @@ enum dev_prop_type {
 	DEV_PROP_MAX,
 };
 
+enum dev_dma_attr {
+	DEV_DMA_NOT_SUPPORTED,
+	DEV_DMA_NON_COHERENT,
+	DEV_DMA_COHERENT,
+};
+
 bool device_property_present(struct device *dev, const char *propname);
 int device_property_read_u8_array(struct device *dev, const char *propname,
 				  u8 *val, size_t nval);