Incorrect shell script syntax in affine-platform.sh

Brief Description
-----------------
The "affine-platform.sh" script in the starlingx/utilities repository has a few instances of the incorrect use of shell syntax. Here is an example:

        PIDLIST=$( ps -e -p 2 |grep rcuc | awk '{ print $1; }')
        for PID in ${PIDLIST[@]}; do
            chrt -p -f 4 ${PID} 2>/dev/null
        done

PIDLIST is initialized to a scalar/non-array value with =$(...), but the for loop uses it like a shell array with ${PIDLIST[@]}, which is the syntax for iterating over elements in a shell array.

The problematic code can be seen here: https://opendev.org/starlingx/utilities/src/commit/53194825c04f2044e1c4cbd606e9df5f3456f736/utilities/worker-utils/worker-utils/affine-platform.sh#L103

Thankfully, this syntactic issue appears to be harmless, but it is confusing to the reader.

Severity
--------
Minor

Steps to Reproduce
------------------
None. This is a shell script syntax issue.

Expected Behavior
------------------
Proper array iteration syntax should be used, such as the following example:
  https://review.opendev.org/c/starlingx/utilities/+/839795

Actual Behavior
----------------
Incorrect shell script syntax.

Reproducibility
---------------
Not applicable.

System Configuration
--------------------
Not applicable.

Branch/Pull Time/Commit
-----------------------
The issue appears to have been introduced with the following commit from 2019:

commit 66355faf0e771b219524b165326fce4dcea4d185
Date: Thu Jun 27 11:47:12 2019 -0400

    AIO reaffine tasks and k8s-infra during startup

Last Pass
---------
Not applicable.

Timestamp/Logs
--------------
Not applicable.

Test Activity
-------------
Code review.

Workaround
----------
None required.