net/xen-netback: off by one in BUG_ON() condition
net/xen-netback: off by one in BUG_ON() condition

The > should be >=.  I also added spaces around the '-' operations so
the code is a little more consistent and matches the condition better.

Fixes: f53c3fe8dad7 ('xen-netback: Introduce TX grant mapping')
Signed-off-by: Dan Carpenter <ff341aa343d564f9e53e9dcb6996be8c04859a66@oracle.com>
Signed-off-by: David S. Miller <fe08d3c717adf2ae63592e4c9aec6e3e404d8e3e@davemloft.net>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs