topdown: Remove carriage returns (^M)

[Treece-Burgess]

Pull Request Description

The topdown component files:

README.md
Rules.topdown
topdown.c
topdown.h

all had carriage returns (^M). This PR removes them.

Testing

Testing was done on Picard at Oregon with the following setup:

• PAPI configure: ./configure --prefix=$PWD/test-install --with-components="topdown" --with-debug=yes
• CPU: Intel Xeon Gold 6430 (SPR)
• OS: RHEL 8.10

Results are as follows:

• PAPI build: ✅
• PAPI utilities*: ✅
• topdown component tests: ✅

* - papi_component_avail, papi_native_avail, papi_command_line

Author Checklist

• Description
  Why this PR exists. Reference all relevant information, including background, issues, test failures, etc
• Commits
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  Commits have a body (whenever relevant) containing a detailed description of the addressed problem and its solution
• Tests
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