staging: unisys: remove leftover __DATE__

Commit 836bee9e ("Staging: unisys: remove references to __DATE__
and __TIME__") removed most; this seems to be an accidental
leftover. VERSIONDATE is not used anywhere.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>