RSE: Add routing tables getter functions

Add functions which abstract the storage location of the RSE routing
tables. These functions can be used in place of tfm_plat_otp_read in
rse_handshake.c.

Change-Id: I5e4290eab1d0b49a58bdf0dfb4d25000d24ecbb2
Signed-off-by: Jackson Cooper-Driver <jackson.cooper-driver@arm.com>
6 files changed