scripts: reset LLEXT VMA accumulators before each west build

llext_link_helper.py uses openmod_module_size and module_size as
persistent counters to assign pre-linked VMAs to LLEXT ELFs.  Running
ninja more than once without a pristine build causes these files to
accumulate across invocations.  The second run doubles the counter
values, placing all ELF VMAs outside the valid LLEXT virtual region
[CONFIG_LIBRARY_BASE_ADDRESS, +CONFIG_LIBRARY_REGION_SIZE).

When pre_located=true the LLEXT loader uses the ELF sh_addr VMAs
directly as physical load addresses.  sys_mm_drv_map_region() silently
fails for out-of-range addresses, so the module is never registered.
The kernel then receives IPC4_MOD_NOT_INITIALIZED (error 104) for every
module init IPC.

Reset both accumulator files to 0 before every west build invocation so
VMA assignment always starts from CONFIG_LIBRARY_BASE_ADDRESS.

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

Author: lrgirdwo

scripts/xtensa-build-zephyr.py

@@ -979,6 +979,20 @@ def build_platforms():
 				env=platf_build_environ, sof_log_env=True)
 		print()
 
+		# Reset the LLEXT VMA accumulator files before every build.
+		# llext_link_helper.py uses openmod_module_size and module_size as
+		# persistent counters across cmake custom-command invocations.  If
+		# ninja is invoked more than once without a pristine rebuild these
+		# counters keep accumulating, pushing pre-linked VMAs beyond the
+		# valid LLEXT virtual region and causing sys_mm_drv_map_region() to
+		# fail silently at runtime (IPC4_MOD_NOT_INITIALIZED error 104).
+		zephyr_build_dir = pathlib.Path(abs_build_dir) / "zephyr"
+		for acc_file in ("openmod_module_size", "module_size"):
+			acc_path = zephyr_build_dir / acc_file
+			if acc_path.is_file():
+				acc_path.write_text("0\n")
+				print(f"Reset LLEXT VMA accumulator: {acc_path}")
+
 		# Build
 		try:
 			execute_command(build_cmd, cwd=west_top, env=platf_build_environ, sof_log_env=True)