[llvm] [TableGen] Print a warning when a Processor contains duplicate Features / TuneFeatures (PR #137864)

[Min-Yih Hsu via llvm-commits]

mshockwave wrote:

> I also see:
> 
> [2704/5914] Building CSKYGenSubtargetInfo.inc... warning: Processor ck807e contains duplicate feature 'edsp' warning: Processor ck807e contains duplicate feature 'dsp1e2' warning: Processor ck807e contains duplicate feature 'dspe60' warning: Processor ck807ef contains duplicate feature 'edsp' warning: Processor ck807ef contains duplicate feature 'dsp1e2' warning: Processor ck807ef contains duplicate feature 'dspe60'

thanks for catching that. PR: #138316 

https://github.com/llvm/llvm-project/pull/137864