[BUG] rimage-extra.args not passed to llext module signing

[kv2019i]

Describe the bug¨
The riamage extra args are not passed to llext module signing in xtensa-build-zephyr.py.

build with extra command:
west config rimage.extra-args '-p -i 4'

Main image build command:
/buildagent/workspace/24951/build-rimage/rimage -o /buildagent/workspace/24951/build-lnl/zephyr/zephyr.ri -k /root/keys/mtl_private_key.pem -f 2.11.0 -b 1 -p -i 4 -e -c /buildagent/workspace/24951/build-lnl/zephyr/misc/generated/rimage_config.toml

Llext build command:

/buildagent/workspace/24951/build-rimage/rimage -o /buildagent/workspace/24951/build-lnl/zephyr/drc_llext/drc.llext.ri -e -c /buildagent/workspace/24951/build-lnl/zephyr/drc_llext/rimage_config.toml -k /root/keys/mtl_private_key.pem -l -r /buildagent/workspace/24951/build-lnl/zephyr/drc_llext/drc.llext

To Reproduce
Build with extra args.

Reproduction Rate
100%

Expected behavior
rimage extra args passed in the same way to both main and module builds.

Impact
Cannot release binaries as modules.

[lyakh]

#9509

[kv2019i]

closed via #9509