ST7735 Fixups

[jkearins]

Hi loboris,

1. My ST7735 display works with DEFAULT_DISP_TYPE as DISP_TYPE_ILI9341 but does not work with DISP_TYPE_ST7735, DISP_TYPE_ST7735B, DISP_TYPE_ST7735R. I corrected the code and now my display works as DISP_TYPE_ST7735B and DISP_TYPE_ST7735R.
2. I think that the init sequence for 7735R in tftspi.c must be:

STP7735R_init
Rcmd2red  (not Rcmd2green)
Rcmd3

3. Also you can add new type 7735G with init sequence:

STP7735R_init
Rcmd2green
Rcmd3

but for Green Label some offsets should be released:

colstart = 2;
rowstart = 1;

Best regards