Partially revert 24d0e21f51

This reverts the extra for loop condition from
"do_iterative_fd_io_iterate(): Support sparse files".

When reading a file with more than 8 block_runs, get_vecs() would
return B_BUFFER_OVERFLOW which would never create any subrequest due
to the test on error == B_OK on the loop, but instead just fail.

Except for the get_vecs() return code, where it is not wanted,
the test made no sense as all other assignments are tested directly
or passed around with break.

Works for me but I don't guarantee it's completely correct.

src/system/kernel/fs/vfs_request_io.cpp

@@ -165,9 +165,7 @@ do_iterative_fd_io_iterate(void* _cookie, io_request* request,
 
 	// create subrequests for the file vecs we've got
 	size_t subRequestCount = 0;
-	for (size_t i = 0;
-		i < vecCount && subRequestCount < kMaxSubRequests && error == B_OK;
-		i++) {
+	for (size_t i = 0; i < vecCount && subRequestCount < kMaxSubRequests; i++) {
 		off_t vecOffset = vecs[i].offset;
 		off_t vecLength = min_c(vecs[i].length, (off_t)requestLength);
 		TRACE_RIO("[%ld]    vec %lu offset: %lld, length: %lld\n",