hw/m68k/Makefile.objs: Conditionally build boards

CONFIG_AN5206, CONFIG_MCF5206 and CONFIG_MCF5208 make
variables created for m68k boards, and added to
default-configs/m86k-softmmu.mak.

Signed-off-by: Ákos Kovács <akoskovacs@gmx.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20190202072456.6468-9-yang.zhong@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

default-configs/m68k-softmmu.mak

@@ -2,3 +2,5 @@
 
 CONFIG_COLDFIRE=y
 CONFIG_PTIMER=y
+CONFIG_AN5206=y
+CONFIG_MCF5208=y

hw/m68k/Makefile.objs

@@ -1,2 +1,2 @@
-obj-y += an5206.o mcf5208.o
-obj-y += mcf5206.o mcf_intc.o
+obj-$(CONFIG_AN5206) += an5206.o mcf5206.o
+obj-$(CONFIG_MCF5208) += mcf5208.o mcf_intc.o