fix: populate test environment variables before first use in run fragment

Commit 4e8aaf1a mistakenly changes the order of declaration of few
environment variables necessary for NVM based FVP reboot tests.

Signed-off-by: Madhukar Pappireddy <madhukar.pappireddy@arm.com>
Change-Id: If057f6f8bf1ff69e2881de4534a66f851b84f846
1 file changed