dmaengine: fix enable for high order unmap pools

The higher order mempools support raid operations, and we want to
disable them when raid support is not enabled.  Making them conditional
on ASYNC_TX_DMA is not sufficient as other users (specifically dmatest)
will also issue raid operations.  Make raid drivers explicitly request
that the core carry the higher order pools.
Reported-by: NEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Tested-by: NEzequiel Garcia <ezequiel.garcia@free-electrons.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

drivers/dma/Kconfig

@@ -62,6 +62,7 @@ config INTEL_IOATDMA
 	tristate "Intel I/OAT DMA support"
 	depends on PCI && X86
 	select DMA_ENGINE
+	select DMA_ENGINE_RAID
 	select DCA
 	help
 	  Enable support for the Intel(R) I/OAT DMA engine present
@@ -112,6 +113,7 @@ config MV_XOR
 	bool "Marvell XOR engine support"
 	depends on PLAT_ORION
 	select DMA_ENGINE
+	select DMA_ENGINE_RAID
 	select ASYNC_TX_ENABLE_CHANNEL_SWITCH
 	---help---
 	  Enable support for the Marvell XOR engine.
@@ -187,6 +189,7 @@ config AMCC_PPC440SPE_ADMA
 	tristate "AMCC PPC440SPe ADMA support"
 	depends on 440SPe || 440SP
 	select DMA_ENGINE
+	select DMA_ENGINE_RAID
 	select ARCH_HAS_ASYNC_TX_FIND_CHANNEL
 	select ASYNC_TX_ENABLE_CHANNEL_SWITCH
 	help
@@ -377,4 +380,7 @@ config DMATEST
 	  Simple DMA test client. Say N unless you're debugging a
 	  DMA Device driver.
 
+config DMA_ENGINE_RAID
+	bool
+
 endif

drivers/dma/dmaengine.c

@@ -912,7 +912,7 @@ struct dmaengine_unmap_pool {
 #define __UNMAP_POOL(x) { .size = x, .name = "dmaengine-unmap-" __stringify(x) }
 static struct dmaengine_unmap_pool unmap_pool[] = {
 	__UNMAP_POOL(2),
-	#if IS_ENABLED(CONFIG_ASYNC_TX_DMA)
+	#if IS_ENABLED(CONFIG_DMA_ENGINE_RAID)
 	__UNMAP_POOL(16),
 	__UNMAP_POOL(128),
 	__UNMAP_POOL(256),