soc: xtensa: fix missing rodata section in intel_s1000

The linker script for the intel_s1000 was missing an include for the
snippets-rodata.ld file which is needed for any applications using the
`zephyr_linker_sources(RODATA <linker_script>)` cmake function.

Signed-off-by: Yuval Peress <peress@google.com>