xtensa-build-zephyr: fix pylint "Redefine 'platform' from outer scope"

Fixes pylint warning `scripts/xtensa-build-zephyr.py:426:5: W0621:
Redefining name 'platform' from outer scope (line 14)
(redefined-outer-name)` and reduce "grep confusion": the script uses
`platform` A LOT.

Signed-off-by: Marc Herbert <marc.herbert@intel.com>

Author: marc-hb

scripts/xtensa-build-zephyr.py

@@ -11,7 +11,7 @@
 import subprocess
 import pathlib
 import errno
-import platform
+import platform as py_platform
 import sys
 import shutil
 import multiprocessing
@@ -35,13 +35,13 @@
 
 sof_version = None
 
-if platform.system() == "Windows":
+if py_platform.system() == "Windows":
 	xtensa_tools_version_postfix = "-win32"
-elif platform.system() == "Linux":
+elif py_platform.system() == "Linux":
 	xtensa_tools_version_postfix = "-linux"
 else:
 	xtensa_tools_version_postfix = "-unsupportedOS"
-	warnings.warn(f"Your operating system: {platform.system()} is not supported")
+	warnings.warn(f"Your operating system: {py_platform.system()} is not supported")
 
 platform_list = [
 	# Intel platforms