refactor(mediatek): refactor plat_sip_calls.h for mt8192/mt8195/mt8186

- MTK_SIP_KERNEL_DFD can be moved to mtk_sip_def.h.
- Remove unused MTK_SIP_* definations which are already defined in
  mtk_sip_def.h.

Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com>
Change-Id: Ife8f1e842d986691488548632426f194199d42b9