Fixup a comment in the overlay driver
Fixup a comment in the overlay driver

Since maxDepth is 500 and not 128, the comment doesn't make sense.
Instead of defining a new named constant, just use the value, since the
choice of 128 was already explained in the paragraph just above it.

Signed-off-by: Nalin Dahyabhai <f562fcb2a0b898bf0be1afc867ea92325d8f825f@redhat.com>

containers/storage,containers/storage,containers/storage