MIPS: IP27: Switch from DMA_IP27 to DMA_COHERENT

The special IP27 DMA code selected by DMA_IP27 has been removed a while
ago turning DMA_IP27 into almost a nop.  Also fixup the broken logic of
its last users memcpy.S and memcpy-inatomic.s.

Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 52c80c2..71e8ebd 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -351,7 +351,7 @@
 	select ARC64
 	select BOOT_ELF64
 	select DEFAULT_SGI_PARTITION
-	select DMA_IP27
+	select DMA_COHERENT
 	select SYS_HAS_EARLY_PRINTK
 	select HW_HAS_PCI
 	select NR_CPUS_DEFAULT_64
@@ -761,9 +761,6 @@
 config DMA_COHERENT
 	bool
 
-config DMA_IP27
-	bool
-
 config DMA_NONCOHERENT
 	bool
 	select DMA_NEED_PCI_MAP_STATE