executorch/{kernel,examples}: fix llvm-17-exposed format mismatches (#6350)

Summary:
Pull Request resolved: https://github.com/pytorch/executorch/pull/6350

This avoids the following errors:

  executorch/examples/portable/custom_ops/custom_ops_1_out.cpp:23:7: error: format specifies type 'char' but the argument has type 'ScalarType' [-Werror,-Wformat]
  executorch/examples/portable/custom_ops/custom_ops_1_out.cpp:27:7: error: format specifies type 'char' but the argument has type 'ScalarType' [-Werror,-Wformat]
  xplat/executorch/kernels/test/custom_kernel_example/op_relu.cpp:90:11: error: format specifies type 'char' but the argument has type 'ScalarType' [-Werror,-Wformat]

Reviewed By: tarun292

Differential Revision: D64577370

fbshipit-source-id: d9e77b2563d21e6e2103467653f9f265a989776f