platform/x86: dell-smbios-wmi: Correct a memory leak

ACPI buffers were being allocated but never freed.

Reported-by: Pinzhen Xu <pinzhen.xu@intel.com>
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Cc: stable@vger.kernel.org
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>