dm integrity: fix out-of-range warning

dm integrity: fix out-of-range warning

Depending on the value of CONFIG_HZ, clang complains about a pointless
comparison:

drivers/md/dm-integrity.c:4085:12: error: result of comparison of
                        constant 42949672950 with expression of type
                        'unsigned int' is always false
                        [-Werror,-Wtautological-constant-out-of-range-compare]
                        if (val >= (uint64_t)UINT_MAX * 1000 / HZ) {

As the check remains useful for other configurations, shut up the
warning by adding a second type cast to uint64_t.

Fixes: 468dfca38b1a ("dm integrity: add a bitmap mode")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Mikulas Patocka <mpatocka@redhat.com>
Reviewed-by: Justin Stitt <justinstitt@google.com>
Signed-off-by: Mike Snitzer <snitzer@kernel.org>