Corrects condition to check valid SERVICE_TYPE

Reasons:
- Currently expr is used to match condition, because of which the if
  part of valid SERVICE_TYPE is used, for eg. "mysq" of "mysql", then
  it is not called as invalid SERVICE_TYPE.

Changes:
- Updates the condition to match SERVICE_TYPE in VALID_SERVICES.

Change-Id: Ia6b1d09d0cb3cf651e08f5c85573e7b32032d9fc
Closes-Bug: #1322612