implement tempcontrol

tempcontrol: sysfs interface for temp sensor threshold control

tempcontrol: always show current temp in sysfs

temp control: setting templimit to 0 will revert to kernel default

tempcontrol: set initial sysfs value to kernel default
make tempcontrol optional (introduce config variable)

Conflicts:
	drivers/misc/Kconfig
Enable temp control and set default limit of 75 degrees