MSC_ConnHdlr: Fix f_rsl_reply() for RSL_MT_ENCR_CMD

In all RSL messages the link identifier is usually the second IE.
However, as the only known exception, the RSL Encryption Command has it
as third IE.

Fixes the following error message:
Dynamic test case error: Using non-selected field link_id in a value of
union type @RSL_Types.RSL_IE_Body

Change-Id: I2bbb83b5394d0b693a47d286beed5c699ab6e8ae
1 file changed