[top/chip] Rename chip-level tops

This renames all target specific toplevels such that they are prefixed
with chip_* instead of top_*. This is done to distinguish the
autogenerated toplevel, which contains all the IPs, crossbar, etc, from
the chiplevel wrappers that are target-specific.

Note that another option would have been to rename
top_<name> -> <name>, but we refrained from doing so as this would
change the definition of what we have so far referred to as the top,
and would have a more profound impact on tooling scripts, generated
headers and packages that use the name top_<name> inline (e.g.
hierarchical paths) or as part of the file name.

Signed-off-by: Michael Schaffner <msf@google.com>
diff --git a/doc/rm/ref_manual_fpga.md b/doc/rm/ref_manual_fpga.md
index aad79e2..f25bacf 100644
--- a/doc/rm/ref_manual_fpga.md
+++ b/doc/rm/ref_manual_fpga.md
@@ -39,13 +39,13 @@
 ```console
 $ cd $REPO_TOP
 $ ./util/fpga/splice_nexysvideo.sh
-$ fusesoc --cores-root . pgm lowrisc:systems:top_earlgrey_nexysvideo
+$ fusesoc --cores-root . pgm lowrisc:systems:chip_earlgrey_nexysvideo
 ```
 
-The script assumes that there is an existing bitfile `build/lowrisc_systems_top_earlgrey_nexysvideo_0.1/synth-vivado/lowrisc_systems_top_earlgrey_nexysvideo_0.1.bit` (this is created after following the steps in [getting_started_fpga]({{< relref "doc/ug/getting_started_fpga" >}})).
+The script assumes that there is an existing bitfile `build/lowrisc_systems_chip_earlgrey_nexysvideo_0.1/synth-vivado/lowrisc_systems_chip_earlgrey_nexysvideo_0.1.bit` (this is created after following the steps in [getting_started_fpga]({{< relref "doc/ug/getting_started_fpga" >}})).
 
 The script rebuilds the contents in `sw/devices/boot_rom` and then creates a new bitfile of the same name at the same location.
-The original input bitfile is moved to `build/lowrisc_systems_top_earlgrey_nexysvideo_0.1/synth-vivado/lowrisc_systems_top_earlgrey_nexysvideo_0.1.bit.orig`.
+The original input bitfile is moved to `build/lowrisc_systems_chip_earlgrey_nexysvideo_0.1/synth-vivado/lowrisc_systems_chip_earlgrey_nexysvideo_0.1.bit.orig`.
 
 The fusesoc command can then be directly invoked to flash the FPGA.
 
@@ -64,7 +64,7 @@
 $ cd ${REPO_TOP}
 $ ./meson_init.sh
 $ ninja -C build-out
-$ build-bin/sw/host/spiflash/spiflash \ 
+$ build-bin/sw/host/spiflash/spiflash \
     --input build-bin/sw/device/examples/hello_world/hello_world_fpga_nexysvideo.bin
 
 Running SPI flash update.