修复Input格式化类型删除时，光标定位问题

[sayll]

First of all, thank you for your contribution! :-)

Please makes sure that these checkboxes are checked before submitting your PR, thank you!

• Make sure that you follow antd's code convention.
• Run npm run lint and fix those errors before submitting in order to keep consistent code style.
• Rebase before creating a PR to keep commit history clear.
• Add some descriptions and refer relative issues for you PR.

Extra checklist:

if isBugFix :

• Make sure that you add at least one unit test for the bug which you had fixed.

elif isNewFeature :

• Update API docs for the component.
• Update/Add demo to demonstrate new feature.
• Update TypeScript definition for the component.
• Add unit tests for the feature.

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This change is 

[codecov]

Codecov Report

Merging #3189 into master will increase coverage by <.01%.
The diff coverage is 75%.

@@            Coverage Diff             @@
##           master    #3189      +/-   ##
==========================================
+ Coverage   60.05%   60.06%   +<.01%     
==========================================
  Files          92       92              
  Lines        2278     2281       +3     
  Branches      654      655       +1     
==========================================
+ Hits         1368     1370       +2     
- Misses        901      902       +1     
  Partials        9        9

Flag	Coverage Δ
#web	60.06% <75%> (ø)	⬆️

Impacted Files	Coverage Δ
components/input-item/index.tsx	63.92% <75%> (+0.05%)	⬆️

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[doxiaodong]

@zack24q