hw: move SSI controllers to hw/ssi/, configure via default-configs/

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
diff --git a/hw/ssi/Makefile.objs b/hw/ssi/Makefile.objs
index daada5c..9555825 100644
--- a/hw/ssi/Makefile.objs
+++ b/hw/ssi/Makefile.objs
@@ -1,2 +1,6 @@
 common-obj-$(CONFIG_PL022) += pl022.o
 common-obj-$(CONFIG_SSI) += ssi.o
+common-obj-$(CONFIG_XILINX_SPI) += xilinx_spi.o
+common-obj-$(CONFIG_XILINX_SPIPS) += xilinx_spips.o
+
+obj-$(CONFIG_OMAP) += omap_spi.o