MLBEDSW-3643: Refactor blockdep calculation

Moved blockdep calculation and other helper functions for
code generation to a separate file.

Change-Id: I2f8ccea478654272ebf42217fc5c1800e9ad177a
Signed-off-by: Louis Verhaard <louis.verhaard@arm.com>
diff --git a/ethosu/vela/test/extapi/test_extapi_generate_commands.py b/ethosu/vela/test/extapi/test_extapi_generate_commands.py
index 812991a..b605dfc 100644
--- a/ethosu/vela/test/extapi/test_extapi_generate_commands.py
+++ b/ethosu/vela/test/extapi/test_extapi_generate_commands.py
@@ -41,7 +41,7 @@
 from ethosu.vela.ethos_u55_regs.ethos_u55_regs import cmd0
 from ethosu.vela.ethos_u55_regs.ethos_u55_regs import cmd1
 from ethosu.vela.register_command_stream_generator import CmdMode
-from ethosu.vela.register_command_stream_generator import get_address_ranges
+from ethosu.vela.register_command_stream_util import get_address_ranges
 
 
 def check_cmd0(cmd_stream, cmd, param):