drc: Export log_dynamic symbol for LLEXT with runtime filtering

Export log_dynamic_drc symbol when CONFIG_LOG_RUNTIME_FILTERING is
enabled to fix LLEXT module linking failure.

When runtime filtering is enabled, LOG_MODULE_REGISTER() creates both
log_const_<module> and log_dynamic_<module> structures. LLEXT modules
need to link against these symbols at load time.

Previously, only log_const_drc was exported, causing the LLEXT linker to
fail with:

<wrn> llext: llext_link_plt: PLT: cannot find idx 46 name log_dynamic_drc
<err> llext: do_llext_load: Failed to link, ret -2
<err> lib_manager: llext_manager_link_single: linking failed: -2

This prevented the DRC module from loading when built as LLEXT with
runtime log filtering enabled.

The fix conditionally exports log_dynamic_drc when runtime filtering is
configured, allowing the LLEXT module to resolve all required logging
symbols.

Signed-off-by: Tomasz Leman <tomasz.m.leman@intel.com>

Author: tmleman

src/audio/drc/drc_log.c

@@ -11,3 +11,6 @@ SOF_DEFINE_REG_UUID(drc);
 LOG_MODULE_REGISTER(drc, CONFIG_SOF_LOG_LEVEL);
 DECLARE_TR_CTX(drc_tr, SOF_UUID(drc_uuid), LOG_LEVEL_INFO);
 EXPORT_SYMBOL(log_const_drc);
+#ifdef CONFIG_LOG_RUNTIME_FILTERING
+EXPORT_SYMBOL(log_dynamic_drc);
+#endif