Remove unreachable return in loadJsonConfig

The loadJsonConfig() function always returns from a valid
version case or throws an exception for unsupported versions.
The trailing return statement is unreachable and misleading.

Change-Id: I27ff767cb5c0ccd82a1cc3422c56eeca7eb7ad56
Signed-off-by: George Liu <liuxiwei@ieisystem.com>