hw/timer/hpet: Drop the unused macro HPET_TN_CFG_BITS_READONLY_OR_RESERVED is not used in any place since HPET_TN_CFG_WRITE_MASK has been already used to check and fix the writable bits in hpet_ram_write(). Drop this unused macro. Signed-off-by: Zhao Liu <zhao1.liu@intel.com> Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org> Reviewed-by: Michael Tokarev <mjt@tls.msk.ru> Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>