sonic-platform-modules-dell s6000 build failure does not cause job build failure

[lguohan]

Description

Steps to reproduce the issue:

1. check the buid log

Describe the results you received:
s6000 build failure should cause the dpkg-buildpackage -uc -ub to fail. However such failure is ignored.

Describe the results you expected:
Please improve the build script not to ignore any error.

Additional information you deem important (e.g. issue happens only occasionally):

**Output of `show version`:**

```
(paste your output here)
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**Attach debug file `sudo generate_dump`:**

```
(paste your output here)
```

[lguohan]

platform-modules-z9100_1.1_amd64.deb.log

[xinliu-seattle]

@padmanarayana to make sure the fix is in.

[padmanarayana]

@santhosh-kt raised #4108