lisa_shell: Run lisa-check-submods only for DEVMODE=1
lisa_shell: Run lisa-check-submods only for DEVMODE=1

...as it rightfully should be. For other cases, it doesn't
make sense to run it, plus it print an annoying warning for
no reason everytime.

Change-Id: I3af35d0d2429a339f98f91fdfd813a36c33f9ad6
Signed-off-by: Joel Fernandes <89f39a38232ac523c7644e47b6ca6563177e40b4@google.com>

credp/lisa,arnoldlu/lisa,ARM-software/lisa,bjackman/lisa,credp/lisa,credp/lisa,bjackman/lisa,mdigiorgio/lisa,ARM-software/lisa,credp/lisa,mdigiorgio/lisa,arnoldlu/lisa,ARM-software/lisa,ARM-software/lisa