product/rdn2: enable sp805 watchdog module

RD-N2 platform and its variants include a SP805 WDT controller
in the SCP sub-system. Add the SP805 module configuration data
for the RD-N2 platform and its variants and enable the use of
the SP805 module on the RD-N2 platforms.

Signed-off-by: Tony K Nadackal <tony.nadackal@arm.com>
Change-Id: Ib1b8725f9b50b05eb7775ff690368bf06558e6fb