When setting the next kernel to boot to with grub, do not opencode
the reboot operation.  The normal reboot operation can be modified by
config options (namely POWERCYCLE_AFTER_REBOOT). This needs to affect
all reboots. Remove the opencoded reboot to make sure that any changes
to the reboot code also affect all reboots.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>