[topgen] Keep creating C files in hw/top_{topname}/sw/autogen
[topgen] Keep creating C files in hw/top_{topname}/sw/autogen

SW doesn't use FuseSoC or check the FuseSoC build folders. It expects these
files always at the same position. For this reason, we need to keep
creating a copy of the files in this folder irrespective of the output
path.

Signed-off-by: Pirmin Vogel <386a7fc8e7338ed7899b4d9883c0ebec5de81366@lowrisc.org>

lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan,lowRISC/opentitan