Staging: vme: Allocate memory buffers for master windows

For VME device I/O operations on master windows the user driver tends
to use kern_buf buffer array which is not allocated. This causes an error
when reading from master window device files.

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>