staging: unisys: Documentation: Remove proc-entries.txt

Unisys drivers no longer utilize procfs. Therefore, the documentation
for our procfs entries is no longer needed.

Signed-off-by: David Binder <david.binder@unisys.com>
Signed-off-by: David Kershner <david.kershner@unisys.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>