[MIPS] Delete unused CONFIG_DMA_IP32.

The functionality of the former dma-ip32.c has been folded into
dma-default.c.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index b22c043..d60bbbb 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -797,10 +797,6 @@
 config DMA_IP27
 	bool
 
-config DMA_IP32
-	bool
-	select DMA_NEED_PCI_MAP_STATE
-
 config DMA_NONCOHERENT
 	bool
 	select DMA_NEED_PCI_MAP_STATE