ACPI: thinkpad-acpi: handle HKEY event 6030

HKEY event 0x6030 is a helper for Lenovo's Advanced Thermal Management
Windows driver, which is, of course, completely undocumented.

Silence any warnings about it being an unknown alarm, and report it
unmodified for userspace.

Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>