ARC: boards: hsdk: disable XIP

XIP (eXecute In Place) is a method of executing programs directly
from long term storage (i.e flash memory). It allows us to
avoid copying text it into RAM, saving writable memory for dynamic
data and not the static program code.

We don't have such non-volatile memory capable for executing in
place on HSDK so we load Zephyr image to DDR memory with debugger
each time.

Disable XIP option for HSDK as we don't need it.

Signed-off-by: Eugeniy Paltsev <Eugeniy.Paltsev@synopsys.com>