x86, reboot: Fix the use of passed arguments in 32-bit BIOS reboot

The initial version of this patch had %eax being a segment and %ecx
being the mode.  I had changed the interfaces, but not the actual
implementation!

Reported-by: Brian Gerst <brgerst@gmail.com>
LKML-Reference: <AANLkTikxqk=HEw9R-Du=v-1ti1HDGAY9vaNUep2XARaz@mail.gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Matthieu Castet <castet.matthieu@free.fr>