Fix comparison warning of integers of different signs (#748)

Summary:
<!--
Thank you for sending the PR! We appreciate you spending the time to work on these changes.

Help us understand your motivation by explaining why you decided to make this change.

You can learn more about contributing to `idb` here: https://github.com/facebook/idb/blob/main/.github/CONTRIBUTING.md

Happy contributing!

-->

## Motivation

The signs of `framesInProcess` (NSInteger) and `MaxAllowedUnprocessedDataCounts` (NSUInteger) do not match, resulting in a warning when comparing.

Pull Request resolved: #748

Test Plan:
(Since we have only fix minor warnings, I don't think we need to test it.)

## Related PRs

Reviewed By: ideahitme

Differential Revision: D32591689

Pulled By: c-ryan747

fbshipit-source-id: 46c1d0b468283c1bf2aaeb6612b0db5dca6682d1

FBControlCore/Utility/FBVideoStream.m

@@ -12,7 +12,7 @@
 #import "FBControlCoreLogger.h"
 #import "FBDataConsumer.h"
 
-static NSUInteger const MaxAllowedUnprocessedDataCounts = 10;
+static NSInteger const MaxAllowedUnprocessedDataCounts = 10;
 
 BOOL checkConsumerBufferLimit(id<FBDataConsumer> consumer, id<FBControlCoreLogger> logger) {
   if ([consumer conformsToProtocol:@protocol(FBDataConsumerAsync)]) {