qcacld-3.0: Remove csr_get_infra_session_id()

Change Ib37eff0591d9c043e62883329c12410fcca67223 ("qcacld-3.0: Remove
sme_get_infra_session_id()") removed the only client of
csr_get_infra_session_id(). Since this function is now unused, remove
it.

Change-Id: I32d0875087ad1f55ec8e8ee2985f7397fefb525d
CRs-Fixed: 2371149
2 files changed