Staging: vme: llseek support in user driver

Provide vme_user_llseek() implementation.

Signed-off-by: Arthur Benilov <arthur.benilov@iba-group.com>
Signed-off-by: Vincent Bossier <vincent.bossier@iba-group.com>
Acked-by: Martyn Welch <martyn.welch@ge.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>