MLK-22866 imx8: Remove the optee shared memory from DDR banks

MLK-22866 imx8: Remove the optee shared memory from DDR banks

Optee has 4MB shared memory at its top space which was assigned to
non-secure OS partition in ATF. By default this memory is added to
u-boot DDR banks and will pass to kernel. This means kernel has possibility
to allocate from this memory for system usage. At same time this memory is
used by optee and mem-remapped by optee kernel driver. So it is possible to
have conflict and cause kernel crash.

Fix the issue by removing the shared memory from u-boot DDR banks. Then it
is not visible for both u-boot and kernel and can avoid such issue.

Signed-off-by: Ye Li <ye.li@nxp.com>
Reviewed-by: Anson Huang <Anson.Huang@nxp.com>
(cherry picked from commit 164279c42de0d058b7abe198cc154ee683087e6a)