mds/Locker.cc: fix dereference after null check

CID 716918 (#1 of 1): Dereference after null check (FORWARD_NULL)
  var_deref_model: Passing null pointer "in" to function
  "MDSCacheObject::state_test(unsigned int) const", which
  dereferences it.

Add check for 'in' before use it.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>
mds/Locker.cc: fix dereference after null check

CID 716919 (#1 of 1): Dereference after null check (FORWARD_NULL)
  var_deref_model: Passing null pointer "cap" to function
  "Capability::inc_suppress()", which dereferences it.

Check for 'cap' before use it as in other places of the function.

Signed-off-by: Danny Al-Gaaf <danny.al-gaaf@bisect.de>