ACPI: thinkpad-acpi: enhance box identification output (v2)

During initialization, thinkpad-acpi outputs some messages to make sure
releavant box identification information is easily available in-line with
the rest of the driver messages.

Enhance those messages to output the alfanumeric model number as well.

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