soc: mediatek: Support reset bit mapping in mmsys driver

soc: mediatek: Support reset bit mapping in mmsys driver

- Reset ID must starts from 0 and be consecutive, but
  the reset bits in our hardware design is not continuous,
  some bits are left unused, we need a map to solve the problem
- Use old style 1-to-1 mapping if .rst_tb is not defined

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Signed-off-by: Hsiao Chien Sung <shawn.sung@mediatek.com>
Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>