west: sign: add support for NXP i.MX8ULP board

Add support for signing i.MX8ULP SOF with Zephyr images with rimage.

Signed-off-by: Zhang Peng <[email protected]>

scripts/west_commands/sign.py

@@ -441,7 +441,7 @@ def sign(self, command, build_dir, build_conf, formats):
         kernel_name = build_conf.get('CONFIG_KERNEL_BIN_NAME', 'zephyr')
 
         # TODO: make this a new sign.py --bootloader option.
-        if target in ('imx8', 'imx8m'):
+        if target in ('imx8', 'imx8m', 'imx8ulp'):
             bootloader = None
             kernel = str(b / 'zephyr' / f'{kernel_name}.elf')
             out_bin = str(b / 'zephyr' / f'{kernel_name}.ri')