Add missing soc/cores/cpu directories to MANIFEST.in

MANIFEST.in

@@ -1,14 +1,29 @@
 graft litex/build/sim
 graft litex/soc/software
 graft litex/soc/cores/cpu/blackparrot
+graft litex/soc/cores/cpu/cortex_m1
+graft litex/soc/cores/cpu/cortex_m3
 graft litex/soc/cores/cpu/cv32e40p
+graft litex/soc/cores/cpu/cv32e41p
+graft litex/soc/cores/cpu/cva5
+graft litex/soc/cores/cpu/cva6
+graft litex/soc/cores/cpu/eos_s3
+graft litex/soc/cores/cpu/femtorv
+graft litex/soc/cores/cpu/firev
+graft litex/soc/cores/cpu/gowin_emcu
+graft litex/soc/cores/cpu/ibex
 graft litex/soc/cores/cpu/lm32
+graft litex/soc/cores/cpu/marocchino
 graft litex/soc/cores/cpu/microwatt
 graft litex/soc/cores/cpu/minerva
 graft litex/soc/cores/cpu/mor1kx
+graft litex/soc/cores/cpu/naxriscv
+graft litex/soc/cores/cpu/neorv32
+graft litex/soc/cores/cpu/openc906
 graft litex/soc/cores/cpu/picorv32
 graft litex/soc/cores/cpu/rocket
 graft litex/soc/cores/cpu/serv
 graft litex/soc/cores/cpu/vexriscv
 graft litex/soc/cores/cpu/vexriscv_smp
 graft litex/soc/cores/cpu/zynq7000
+graft litex/soc/cores/cpu/zynqmp