hw: move target-independent files to subdirectories

This patch tackles all files that are compiled once, moving
them to subdirectories of hw/.

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/default-configs/mips64-softmmu.mak b/default-configs/mips64-softmmu.mak
index a5b6c3c..0968e5f 100644
--- a/default-configs/mips64-softmmu.mak
+++ b/default-configs/mips64-softmmu.mak
@@ -18,7 +18,7 @@
 CONFIG_FDC=y
 CONFIG_ACPI=y
 CONFIG_APM=y
-CONFIG_DMA=y
+CONFIG_I8257=y
 CONFIG_PIIX4=y
 CONFIG_IDE_ISA=y
 CONFIG_IDE_PIIX=y