Enable HPET MMAP access by default

configname: CONFIG_HPET_MMAP_DEFAULT

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Enable HPET MMAP access by default
In linux kernel since version 3.13 (release Date: 2014-01-19)  
In some hardware implementations, the page containing HPET
registers may also contain other things that shouldn't be
exposed to the user. This option selects the default (if
kernel parameter hpet_mmap is not set) user access to the
registers for applications that require it.