fix(module: carousel): fix carousel selectedIndex init work error

[Guoyuanqiang]

PR Checklist

Please check if your PR fulfills the following requirements:

• The commit message follows our guidelines: https://github.com/NG-ZORRO/ng-zorro-antd-mobile/blob/master/CONTRIBUTING.md#commit
• Tests for the changes have been added (for bug fixes / features)
• Docs have been added / updated (for bug fixes / features)

PR Type

What kind of change does this PR introduce?

[x] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Build related changes
[ ] CI related changes
[ ] Documentation content changes
[ ] Application (the showcase website) / infrastructure changes
[ ] Other... Please describe:

What is the current behavior?

Issue Number: N/A

What is the new behavior?

Does this PR introduce a breaking change?

[ ] Yes
[x] No

Other information

[codecov]

Codecov Report

Merging #230 into master will decrease coverage by 0.01%.
The diff coverage is 50%.

@@            Coverage Diff             @@
##           master     #230      +/-   ##
==========================================
- Coverage   86.47%   86.46%   -0.02%     
==========================================
  Files         224      224              
  Lines        7298     7298              
  Branches     1024     1024              
==========================================
- Hits         6311     6310       -1     
  Misses        588      588              
- Partials      399      400       +1

Impacted Files	Coverage Δ
components/carousel/carousel.component.ts	76.47% <50%> (-0.37%)	⬇️

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