silence clib_mem_unaligned() invalid read found by address-sanitizer

silence clib_mem_unaligned() invalid read found by address-sanitizer

clib_mem_unaligned + zap64 casts its input as u64, computes a mask
according to the input length, and returns the casted maked value.
Therefore all the 8 Bytes of the u64 are systematically read, and
the invalid ones are discarded.

Since they are discarded correctly, this invalid read can safely be
ignored.

Revert "fix clib_mem_unaligned() invalid read"
This reverts commit 0ed3d81a5fa274283ae69b69a405c385189897d3.

Change-Id: I5cc33ad36063c414085636debe93707d9a75157a
Signed-off-by: Gabriel Ganne <gabriel.ganne@enea.com>