scripts: delete module_size accumulator before each west build

llext_offset_calc.py uses module_size as a persistent counter across
cmake custom-command invocations.  Running ninja more than once without
a pristine build causes the counter to accumulate, placing all pre-linked
LLEXT ELF VMAs outside the valid 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.

Delete module_size before every west build invocation so VMA assignment
always starts from CONFIG_LIBRARY_BASE_ADDRESS.  llext_offset_calc.py
already handles a missing file as size=0 (OSError except clause), so
deletion is the simplest reset.

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

Author: lrgirdwo

scripts/xtensa-build-zephyr.py

@@ -986,6 +986,22 @@ def build_platforms():
 				env=platf_build_environ, sof_log_env=True)
 		print()
 
+		# Delete the LLEXT VMA accumulator file before every build.
+		# llext_offset_calc.py uses module_size as a persistent counter
+		# across cmake custom-command invocations.  If ninja is invoked
+		# more than once without a pristine rebuild this counter keeps
+		# 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).
+		# llext_offset_calc.py already handles a missing file as size=0,
+		# so deletion is the simplest and most reliable reset.
+		zephyr_build_dir = pathlib.Path(abs_build_dir) / "zephyr"
+		if zephyr_build_dir.is_dir():
+			acc_path = zephyr_build_dir / "module_size"
+			if acc_path.is_file():
+				acc_path.unlink()
+				print(f"Deleted LLEXT VMA accumulator: {acc_path}")
+
 		# Build
 		try:
 			execute_command(build_cmd, cwd=west_top, env=platf_build_environ, sof_log_env=True)