Cleanup: Remove branches that always evaluate the same way

Coverity reported that the ASSERT in taskq_create() is always true and
the `*offp > MAXOFFSET_T` check in zfs_file_seek() is always false.

We delete them as cleanup.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Richard Yao <richard.yao@alumni.stonybrook.edu>
Closes #14130

module/os/linux/spl/spl-taskq.c

@@ -1048,7 +1048,6 @@ taskq_create(const char *name, int threads_arg, pri_t pri,
 
 	ASSERT(name != NULL);
 	ASSERT(minalloc >= 0);
-	ASSERT(maxalloc <= INT_MAX);
 	ASSERT(!(flags & (TASKQ_CPR_SAFE))); /* Unsupported */
 
 	/* Scale the number of threads using nthreads as a percentage */