Remove functions calling the deprecated _MM_SET_FLUSH_ZERO_MODE

[rainiwu]

From rust-lang/stdarch#1454, it seems that setting _MM_SET_FLUSH_ZERO_MODE results in "immediate Undefined Behavior", and as a result these functions were deprecated with 1.75.0. This PR removes the functions that include calls to _MM_SET_FLUSH_ZERO_MODE, fixing the warnings thrown when compiling on Rust versions 1.75.0 and newer.

[swfsql]

The other error (error[E0277]: the trait bound cuda::device::Cuda: Conv1DKernel<f32> is not satisfied) seems to be related to this:

dfdx/dfdx-core/src/tensor_ops/conv1d/mod.rs

Lines 4 to 5 in 4722a99

	#[cfg(all(not(feature = "cudnn"), feature = "cuda"))]
	mod cuda_kernel;

I'm new to cuda/cudnn, but it appears that the cuda implementation of Conv1DKernel is behind that cfg condition.
I believe that to solve this, the same condition (#[cfg(all(not(feature = "cudnn"), feature = "cuda"))]) should be present on the Conv1DKernel Device bound, relaxing it for the cudnn case:

dfdx/dfdx-core/src/tensor_ops/utilities/device.rs

Lines 116 to 117 in 4722a99

	// conv1d
	+ super::super::conv1d::Conv1DKernel<E>

[coreylowman]

According to the new documentation of these functions, it seems like this functionality can be achieved with inline assembly? I'd much prefer that than entirely removing these functions.

[swfsql]

I didn't read much material on this - but I'm afraid that every float operations would need to be implemented in asm (not sure)? if this is the case, I think this would require a lot of effort.

Could this be deferred to a later issue? Because if not, the CI would be blocking all prs until this is resolved.
From their discussion, they considered outright removing the functions (instead of deprecating it), so I think that leaving the code unchanged is not recommended.