CPU: fallback to FP32 when FP16 Softmax is unsupported

[VaishnaviOnPC]

Details:

FP16 Softmax on CPU may fail with "Supported primitive descriptors list is empty" when Softmax is a model output.
This change retries descriptor creation using FP32 when FP16 is requested but unsupported by oneDNN.

Tested locally with a minimal FP16 ONNX Softmax model on CPU.

Tickets:

• [Bug]: Supported primitive descriptors list is empty for FLOAT16 Softmax when output is a model output #33381

[maxnick]

@nshchego , could you please review?

[nshchego]

Please add appropriate test case

[VaishnaviOnPC]

I have added the test, please review.

[praasz]

Suggested change

	for (auto format : getAvailableFormatsForDims(inShape)) {
	auto in_candidate = std::make_shared<DnnlBlockedMemoryDesc>(inShape, fallbackType, format);
	if (in_candidate->blocksExtended()) {
	continue;
	}
	createDescriptor({in_candidate}, {});
	}
	for (auto format : getAvailableFormatsForDims(inShape)) {
	VecMemoryDescs inputDescs{std::make_shared<DnnlBlockedMemoryDesc>(inShape, fallbackType, format)};
	if (!inputDescs.back()->blocksExtended()){
	createDescriptor(inputDescs, {});
	}
	}

?

[VaishnaviOnPC]

Hi, I tried the suggestion. All the tests passed. I have made the commit with this change applied.