[platform] Update path to udevprefix.conf file

[jleveque]

Why I did it

sonic-net/sonic-utilities#1431 changes the path to the udevprefix.conf file. The file previously inappropriately resided in the <platform>/plugins/ directory. That directory is reserved for now-deprecated Python platform plugins, and will be removed in the near future.

How I did it

Update all references to udevprefix.conf to reflect the new path, directly under the <platform>/ directory

Note that this PR requires sonic-net/sonic-utilities#1431. For the master branch, this means that this PR should be merged at the same time as the sonic-utilities submodule update here: #6777. For the 202012 branch, this change should be cherry-picked along with an updated 202012 branch of sonic-utilities which includes the respective commit there.

How to verify it

Ensure the udevprefix.conf is now found under the <platform>/ directory

Which release branch to backport (provide reason below if selected)

• 201811
• 201911
• 202006
• 202012

[lguohan]

@jleveque , how is this change tested? have you tried this on e1031 box?
@Blueve for awareness, this could potentially affect e1031 c0.

[jleveque]

@jleveque , how is this change tested? have you tried this on e1031 box?
@Blueve for awareness, this could potentially affect e1031 c0.

The changes were not tested on an e1031 box. However, I did test the isolated changes on another device and ensured that this script now creates the udevprefix.conf file in the <platform> directory and that the consutil changes now cause it to look for the file in that directory. Therefore the changes should be seamless.