testsuite: depmod: check netsted loops reporting

testsuite: depmod: check netsted loops reporting

The patch adds nested loops configuration for the loop test:

mod-loop-h -> mod-loop-i -> mod-loop-j -> mod-loop-k
   ^                           |               |
    ---------------------------                |
   |                                           |
    -------------------------------------------

making 2 loops with common edges:

mod-loop-h -> mod-loop-i -> mod-loop-j -> mod-loop-h
mod-loop-h -> mod-loop-i -> mod-loop-j -> mod-loop-k -> mod-loop-h

The actual output for the loops is:

depmod: ERROR: Cycle detected: mod_loop_h -> mod_loop_h
depmod: ERROR: Cycle detected: mod_loop_i -> mod_loop_j -> mod_loop_k -> mod_loop_h -> mod_loop_i

(the order in the second doesn't matter, but the first one is
incorrect)

Signed-off-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>