Update the e-mail address of Bart Van Assche

Since my @wdc.com e-mail address will become invalid after Friday
August 24th, change it into an e-mail address that will remain valid
after that date.

Signed-off-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>