build.config.msm.common: remove empty lines from system module list files

Commit 416a0f5d4f ("ANDROID: GKI: Convert USB ACM as GKI module")
introduced an empty line in system DLKM list and we end up with
empty modules.load file which eventually busted second stage module
loading.
To avoid such issues, remove empty lines from system module list files.

Change-Id: Ied2d09d04ae84db4c9998d0214a90bfdb4ffa744
Signed-off-by: Tengfei Fan <quic_tengfan@quicinc.com>

build.config.msm.common

@@ -174,7 +174,7 @@ if [[ "${PREPARE_SYSTEM_DLKM}" == "1"  && ! -z "${SYSTEM_DLKM_MODULES_LIST}" ]];
   {
     awk -F'/' '{print $NF}' ${SYSTEM_DLKM_MODULES_LIST}
     [ -f "${MODULES_LIST}" ] && cat "${MODULES_LIST}"
-  } > ${COMBINED_MODULE_LIST}
+  } | sed -e '/^$/d' > ${COMBINED_MODULE_LIST}
 fi
 
 function prepare_vendor_dlkm() {