TCL print_var support for unset variable
TCL print_var support for unset variable

If var_value is not defined, catch the error and print its value as
"** variable not set **".

Change-Id: I437ce0c08dd17e92704776e58e8aaf55de4141fa
Signed-off-by: Michael Walsh <10404802c7de463f402c4a18638106ca1b12ef61@us.ibm.com>

openbmc/openbmc-test-automation,openbmc/openbmc-test-automation