Compile sound devices only once

Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
diff --git a/default-configs/mips-softmmu.mak b/default-configs/mips-softmmu.mak
index 5d1c098..345a093 100644
--- a/default-configs/mips-softmmu.mak
+++ b/default-configs/mips-softmmu.mak
@@ -15,3 +15,4 @@
 CONFIG_IDE_ISA=y
 CONFIG_IDE_PIIX=y
 CONFIG_NE2000_ISA=y
+CONFIG_SOUND=y