ggml : sync latest (new ops, macros, refactoring) (ggml-org#2106)

- add ggml_argmax()
- add ggml_tanh()
- add ggml_elu()
- refactor ggml_conv_1d() and variants
- refactor ggml_conv_2d() and variants
- add helper macros to reduce code duplication in ggml.c

Author: ggerganov