MLECO-6380: Moving to latest ExecuTorch

Updating ExecuTorch submodule to the latest version. The
Arm AOT compiler within ExecuTorch source tree doesn't need
path to the shared lib as it previously did. All references
to this lib used for PTE file generation have been removed.

Additionally, the linking hierarchy for ExecuTorch libs has
been amended to make it simpler to link to.

Change-Id: I1d80e5a6d16666d5106c57f7d9b94c9d0f4f4b6a
Signed-off-by: Kshitij Sisodia <kshitij.sisodia@arm.com>