platform/x86: alienware-wmi: Correct a memory leak

BugLink: https://bugs.launchpad.net/bugs/1798617

commit ff0e9f26 upstream.

An ACPI buffer that was allocated was not being freed after use.
Signed-off-by: Mario Limonciello <mario.limonciello@dell.com>
Cc: stable@vger.kernel.org
Signed-off-by: Darren Hart (VMware) <dvhart@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/platform/x86/alienware-wmi.c

@@ -463,6 +463,7 @@ static acpi_status alienware_hdmi_command(struct hdmi_args *in_args,
 		if (obj && obj->type == ACPI_TYPE_INTEGER)
 			*out_data = (u32) obj->integer.value;
 	}
+	kfree(output.pointer);
 	return status;
 
 }