Timer event to keep grub msec counter was running at 1000HZ. This was too
fast for UEFI timer driver and resulted in a 10x slowdown in grub time
versus wallclock. Reduce the timer event frequency and increase tick
increment accordingly to keep better time.
The current code for EFI grub_exit() calls grub_efi_fini() before
returning to firmware. In the case of ARM, this leaves a timer
event running which could lead to a firmware crash. This patch
changes this so that grub_machine_fini() is called with a NORETURN
flag. This allows machine-specific shutdown to happen as well
as the shutdown done by grub_efi_fini().
Signed-off-by: Mark Salter <msalter@redhat.com>
