[prim] Remove primgen and replace with virtual cores

Add back prim_pkg enum for legacy support, and mention that it is
deprecated. Some IPs reference the enums directly.

Signed-off-by: Alexander Williams <[email protected]>

Author: a-will

hw/ip/prim/prim.core

@@ -13,7 +13,6 @@ filesets:
       - lowrisc:prim:util
       - lowrisc:prim:diff_decode # for prim_alert_sender/receiver
       - lowrisc:prim:pad_wrapper
-      - lowrisc:prim:prim_pkg
       - lowrisc:prim:clock_mux2
       - lowrisc:prim:clock_inv
       - lowrisc:prim:buf

hw/ip/prim/prim_and2.core

@@ -8,7 +8,7 @@ description: "2-input glitch free clock multiplexer"
 filesets:
   files_rtl:
     depend:
-      - lowrisc:prim:prim_pkg
+      - lowrisc:prim:clock_gating
     files:
       - rtl/prim_clock_gp_mux2.sv
     file_type: systemVerilogSource