[PATCHv2] make mc13783 regulator code generic

[Yong Shen]

 Hi there,

This is the v2 with some changes according to comments from v1. There
will be few patches coming out after this one, for mc13892 regulator
to share some code with mc13783.

Still, cause the firewall problem, I send out patch this way. Please
give comments inline and use attached patch for testing.

Yong