arc: Add CONFIG_HARVARD since some ARC CPU Architectures are Harvard.

Some ARC SOC implementations will need CONFIG_HARVARD so as to
select a different initial stack pointer (one at the top of DCCM memory),
and also to select a different linker command file that uses
ICCM and DCCM. Quark_se_ss will have HARVARD equal to n.

Change-Id: Idb7c4126866c9604e1924200ad5fdd2bc9d28269
Signed-off-by: Chuck Jordan <cjordan@synopsys.com>