commit 49f456b1dea55acd41e3cecefd6621d7d5431653
author Patrick Williams <patrick@stwcx.xyz> Wed Nov 11 11:04:05 2020 -0600
committer Patrick Williams <patrick@stwcx.xyz> Wed Nov 11 11:06:11 2020 -0600
tree 82a686b8b2c67000bb931b4646370b3d172745b9
parent 384d741b9e04fce8d6a56e56ff4eeeac195570a9

run-robot.sh: correct invalid variable execution

Commit 384d741 attempted to clean up some issues reported by shellcheck
and ended up causing this script to fail execution.  The previous
variable expansion was non-obvious and warned by shellcheck.  Replaced
with an 'eval' call which seems to behave correctly and not be warned.

Tested:

Confirmed correct execution and error codes from the below executions.

```
ROBOT_TEST_CMD="echo this should pass && echo this also" \
    ./scripts/run-reboot.sh
ROBOT_TEST_CMD="echo this should pass && echo this also && false" \
    ./scripts/run-robot.sh
```

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: Ic4cb55c929511353d3e055d5238c0bcd520a4641