xen-blkback: remove redundant assignment to variable i

xen-blkback: remove redundant assignment to variable i

Variable i is being assigned a value that is never read, it is being
re-assigned later in a for-loop. The assignment is redundant and can
be removed.

Cleans up clang scan build warning:
drivers/block/xen-blkback/blkback.c:934:14: warning: Although the value
stored to 'i' is used in the enclosing expression, the value is never
actually read from 'i' [deadcode.DeadStores]

Signed-off-by: Colin Ian King <colin.i.king@gmail.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>
Link: https://lore.kernel.org/r/20220317234646.78158-1-colin.i.king@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>