Fix unused variable warning in ocs_cam.c

With clang 15, the following -Werror warning is produced:

sys/dev/ocs_fc/ocs_cam.c:2556:11: error: variable 'count' set but not used [-Werror,-Wunused-but-set-variable]
        uint32_t        count;
                        ^

The 'count' variable seems to be a left-over from some debugging code
that no longer exists, and can be removed without any functional change.

MFC after: 3 days

(cherry picked from commit 8d9e29284627f5e860b7fc194e9fedd6b21f7783)