aosp_trout_arm64.mk: Pick up BOARD_VENDOR_RAMDISK_KERNEL_MODULES_DIR cmdline

Linux kernel modules in the dir will be used to populate vendor_boot
ramdisk.

Bug: 225304945
Test: Set the variable and build. Check that modules propagated to the
vendor ramdisk

Change-Id: Ia0805c7ebeeedbdf75d5e1120bb3721a74674e2c
diff --git a/aosp_trout_arm64.mk b/aosp_trout_arm64.mk
index 42c44b6..027c894 100644
--- a/aosp_trout_arm64.mk
+++ b/aosp_trout_arm64.mk
@@ -32,6 +32,10 @@
 TARGET_KERNEL_PATH ?= $(TROUT_KERNEL_IMAGE)
 endif
 
+ifneq ($(BOARD_VENDOR_RAMDISK_KERNEL_MODULES_DIR),)
+BOARD_VENDOR_RAMDISK_KERNEL_MODULES := $(wildcard $(BOARD_VENDOR_RAMDISK_KERNEL_MODULES_DIR)/*.ko)
+endif
+
 # Audio HAL
 TARGET_USES_CUTTLEFISH_AUDIO ?= false
 AUDIO_FEATURE_HFP_ENABLED ?= true