Only compile esp when one target uses it

Patchworks-ID: 35206
Signed-off-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
diff --git a/default-configs/mips64-softmmu.mak b/default-configs/mips64-softmmu.mak
index de64165..2896675 100644
--- a/default-configs/mips64-softmmu.mak
+++ b/default-configs/mips64-softmmu.mak
@@ -1,3 +1,4 @@
 # Default configuration for mips64-softmmu
 
 CONFIG_ISA_MMIO=y
+CONFIG_ESP=y