bancha: add missing dep to create host directory

Bypass-Presubmit-Reason: no presubmit flow for this (only seen w/ m simulate and an empty build area)

Change-Id: If08cb076d35814d4d13350bffe672b1d74757363

platforms/bancha/sim.mk

diff --git a/platforms/bancha/sim.mk b/platforms/bancha/sim.mk
index 9a58e6f..268b435 100644
--- a/platforms/bancha/sim.mk
+++ b/platforms/bancha/sim.mk
@@ -69,7 +69,9 @@
 
 TEST_PRIVATE_KEY_0 := ${OPENTITAN_SOURCE}/sw/device/silicon_creator/rom/keys/fake/test_key_0_rsa_3072_exp_f4.der
 
-opentitantool_: opentitantool_pkg
+$(OUT)/host:
+	mkdir $(OUT)/host
+opentitantool_: opentitantool_pkg | ${OUT}/host
 	tar -C ${OUT}/host -xf $(MATCHA_OUT_DIR)/opentitantool_pkg.tar.gz
 
 ## Construct a 2nd-level OpenTitan firmware image from a cheriot-rtos