lmb: add a check to prevent memory overrun

lmb: add a check to prevent memory overrun

When printing the LMB flags for a memory region, there is a need to
check that the array index that is computed is a sane value. Put a
noisy assert in case this check fails, as that implies something with
the LMB code is not working as expected.

Reported-by: Coverity (CID 510463)
Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>