dectmngr: Support DECT FW per target

Add support for installing default DECT FW per target. This solves the need
to be able to have different default FW for different hardware architectures.

For Airoha we will update the DECT FW to DSPG 4.13 build 21 RC1.

dectmngr/Makefile

@@ -56,11 +56,16 @@ endif
 
 define Package/$(PKG_NAME)/install
 	$(INSTALL_DIR) $(1)/usr/sbin
-	$(INSTALL_DIR) $(1)/etc
+	$(INSTALL_DIR) $(1)/etc/dspg
 	$(INSTALL_DIR) $(1)/lib/upgrade/keep.d
 
 	$(INSTALL_BIN) $(PKG_BUILD_DIR)/app/dectmngr $(1)/usr/sbin/
 	$(STRIP) $(1)/usr/sbin/dectmngr
+ifneq ($(CONFIG_TARGET_airoha),)
+	$(CP) ./firmware/airoha/* $(1)/etc/dspg/
+else
+	$(CP) ./firmware/common/* $(1)/etc/dspg/
+endif
 	$(CP) ./files/etc/* $(1)/etc/
 	$(INSTALL_DATA) ./files/lib/upgrade/keep.d/dect $(1)/lib/upgrade/keep.d/dect
 endef