systemc: Replace some calls to some Accellera specific functions in TLM.

systemc: Replace some calls to some Accellera specific functions in TLM.

The TLM event finder class was calling implementation specific
functions from the Accellera version of systemc. This change replaces those
calls with equivalent calls which match the gem5 implementation.

Change-Id: I0ecdb0a4bf09aeb1aad823a01105fbd88edb4601
Reviewed-on: https://gem5-review.googlesource.com/c/15075
Reviewed-by: Anthony Gutierrez <anthony.gutierrez@amd.com>
Maintainer: Anthony Gutierrez <anthony.gutierrez@amd.com>