V4L/DVB (6503): pvrusb2: Fix associativity logic error

if(!x & y) should either be if(!(x & y)) or if(!x && y)
    I made changes as seemed appropriate, but please review
    this is against current git.

Signed-off-by: Roel Kluin <12o3l@tiscali.nl>
Signed-off-by: Mike Isely <isely@pobox.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>