ACPI: acpi_watchdog: use LIST_HEAD for stack-allocated list

ACPI: acpi_watchdog: use LIST_HEAD for stack-allocated list

Replace the separate declaration of 'resource_list' and subsequent
INIT_LIST_HEAD() call with LIST_HEAD(), which declares and initializes
the list head in one idiomatic step. This reduces code verbosity and
aligns with common kernel coding patterns, without functional change.

Signed-off-by: Can Peng <pengcan@kylinos.cn>
[ rjw: Subject edits ]
Link: https://patch.msgid.link/20251209072757.3110467-1-pengcan@kylinos.cn
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>