gdb/testsuite: fix xfail in gdb.ada/ptype_tagged_param.exp

I see:

    ERROR: wrong # args: should be "xfail message"
        while executing
    "xfail "no debug info" $gdb_test_name"
        ("uplevel" body line 3)
        invoked from within
    "uplevel {
            if {!$has_runtime_debug_info} {
                xfail "no debug info" $gdb_test_name
            } else {
                fail $gdb_test_name
            }
        }"

This is because the xfail takes only one argument, fix that.

Change-Id: I2e304d4fd3aa61067c04b5dac2be2ed34dab3190