Add missing return statement to drvHostBaseScsiCmdOs() following upstream
SVN rev 64316

--- src/VBox/Devices/Storage/DrvHostBase-freebsd.cpp.orig	2020-09-17 22:17:20.129984000 +0200
+++ src/VBox/Devices/Storage/DrvHostBase-freebsd.cpp	2020-09-17 22:21:46.658979000 +0200
@@ -149,6 +149,8 @@
         else
             rc = RTErrConvertFromErrno(errno);
     }
+
+    return rc;
 }