fix: set reports to email as blank if reports to is removed

[MyuddinKhatri]

Issue - https://bloomstack.com/desk#Form/Issue/ISS-2021-00331

• Fixes
• Patches(not required)
• Test Cases(not required)

Traceback/Bug Report:

If reports to is removed from employee still reports_to_email data remained

Steps to replicate:

• Step 1 : Go to Employee List
• Step 2 : Select an Employee
• Step 3 : Add reports to (it fetches reports to email) and save
• Step 4 : Now remove reports to and save it still saves with reports_to_email data

...

Expected Behaviour/Fixes:

Now if Reports To is data is removed then it empties reports to email as well