Add initial support for Ingenic X1000 SoC and Y&A CU Neo board v7.

[周琰杰 (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>]

v6->v7:
1.Merge [05/12],[07/12],[09/12],[11/12] in v6 to [5/6] in v7.
2.Merge [06/12],[08/12],[10/12],[12/12] in v6 to [5/6] in v7.
3.Change my Signed-off-by from "Zhou Yanjie <zhouyanjie@xxxxxxxx>"
  to "周琰杰 (Zhou Yanjie) <zhouyanjie@xxxxxxxxxxxxxx>" because
  the old mailbox is in an unstable state.