This reverts commit 43030db5ff.
For a synthesis tool, generating EG_LOGIC cells are a good choice, as
they can be furtherly optimized when PnR, although sometimes EG_LOGIC is
not as blackbox as EG_PHY cells (because the latter is more close to the
hardware implementation).
Signed-off-by: Icenowy Zheng <icenowy@aosc.io>