arduino_101: fix default ROM size

With the default of 192, the x86 rom will span from
0x40010000 - 0x4004000. However the default starting
ROM address for the ARC side is configured to be
0x40034000. If the x86 image is large enough it will
clobber the ARC code. Shorten the x86 side such that
its last flash address is 0x40033FFF.

Change-Id: I23987c3db11f0e51c2405b8baee114aee39de571
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>