scripts/vagrant: Don't expect an argument for -u option

This is a bool, hence it doesn't require any additional
arguments.

Change-Id: Ibc438f77c5c63ec5dc38007826268a494d8e661d
Signed-off-by: Michal Berger <michalx.berger@intel.com>
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/4239
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>

scripts/vagrant/create_vbox.sh

@@ -84,7 +84,7 @@ VAGRANT_PASSWORD_AUTH=0
 VAGRANT_PACKAGE_BOX=0
 VAGRANT_HUGE_MEM=0
 
-while getopts ":b:n:s:x:p:u:vcraldoHh-:" opt; do
+while getopts ":b:n:s:x:p:uvcraldoHh-:" opt; do
 	case "${opt}" in
 		-)
 			case "${OPTARG}" in