mips,unicore32: swiotlb doesn't need sg->dma_length

Only mips and unicore32 select CONFIG_NEED_SG_DMA_LENGTH when building
swiotlb.  swiotlb itself never merges segements and doesn't accesses the
dma_length field directly, so drop the dependency.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: James Hogan <jhogan@kernel.org>

arch/mips/cavium-octeon/Kconfig

@@ -70,7 +70,6 @@ config CAVIUM_OCTEON_LOCK_L2_MEMCPY
 config SWIOTLB
 	def_bool y
 	select DMA_DIRECT_OPS
-	select NEED_SG_DMA_LENGTH
 
 config OCTEON_ILM
 	tristate "Module to measure interrupt latency using Octeon CIU Timer"

arch/mips/loongson64/Kconfig

@@ -135,7 +135,6 @@ config SWIOTLB
 	default y
 	depends on CPU_LOONGSON3
 	select DMA_DIRECT_OPS
-	select NEED_SG_DMA_LENGTH
 	select NEED_DMA_MAP_STATE
 
 config PHYS48_TO_HT40

arch/unicore32/mm/Kconfig

@@ -43,4 +43,3 @@ config CPU_TLB_SINGLE_ENTRY_DISABLE
 config SWIOTLB
 	def_bool y
 	select DMA_DIRECT_OPS
-	select NEED_SG_DMA_LENGTH