RSL_Emulation: fix rx of tr_RSL_PAGING_CMD()

For tr_RSL_PAGING_CMD, also check comp_ref against null.

Upon receiving a tr_RSL_PAGING_CMD, the code tries to dispatch the Paging
Command to all valid clients. However, the ConnectionTable[*].comp_ref is
*always* present, and actually null for unconnected clients.
So, before this patch, a Paging Command from osmo-bsc gets sent to a null
client, which disconnects the RSL emulation and aborts the test.

There is currently no test using this, but the upcoming MSC pool tests will:
see I21cbab193cd0de2e5692665442eae113d5f61904.

Change-Id: Iaf7730153a3a19e448a33298c3e12212a55929d5
1 file changed