tests: mem_protect/mem_map: remove unused assignment to cnt
tests: mem_protect/mem_map: remove unused assignment to cnt

The variable cnt is assigned twice in a row, so remove
the first one.

Coverity-CID: 235962
Fixes #35161

Signed-off-by: Daniel Leung <d94e04d205b5962d7873a139ef298b03c1717f72@intel.com>

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