The "safe" variant of the hook to read the timer is no longer used and
can be removed. Instead, initialize the get_timecount member of
acpi_timer_timecounter to the normal hook statically. While here,
initialize a few more fields in acpi_timer_timecounter statically.
I've kept the name as just "ACPI" instead of "ACPI-fast" now.
During device probe there is no longer any reason to alloc the
register resource since it is not used, so remove all that. While
here, defer registration of the timecounter until attach (kind of odd
to do such a thing during probe leaving a window where the timer
register was unallocated but in theory could still be read via the
timecounter).
Fixes: 00d061855deb ("Garbage-collect ACPI-safe timer and friends")