LCD core move buf ptr and address look up function viewport struct

I'm currently running up against the limitations of the lcd_draw functions
I want these functions to be able to be used on any size buffer not
just buffers with a stride matching the underlying device

[DONE] allow the framebuffer to be decoupled from the device framebuffer
[DONE need examples] allow for some simple blit like transformations
[DONE] remove the device framebuffer from the plugin api
[DONE}ditto remote framebuffer
[DONE] remove _viewport_get_framebuffer you can call struct *vp = lcd_set_viewport(NULL) and vp->buffer->fb_ptr

while remote lcds may compile (and work in the sim) its not been tested on targets

[FIXED] backdrops need work to be screen agnostic

[FIXED] screen statusbar is not being combined into the main viewport correctly yet

[FIXED] screen elements are displayed incorrectly  after switch to void*

[FIXED] core didn't restore proper viewport on splash etc.

[NEEDS TESTING] remote lcd garbled data

[FIXED] osd lib garbled screen on bmp_part

[FIXED] grey_set_vp needs to return old viewport like lcd_set_viewport

[FIXED] Viewport update now handles viewports with differing buffers/strides by copying to the main buffer

[FIXED] splash on top of WPS leaves old framebuffer data (doesn't redraw)
[UPDATE] refined this a bit more to have clear_viewport set the clean bit and have skin_render do its own screen clear
scrolling viewports no longer trigger wps refresh
also fixed a bug where guisyncyesno was displaying and then disappearing

[ADDED!] New LCD macros that allow you to create properly size frame buffers in you desired size without wasting bytes
(LCD_ and LCD_REMOTE_)
LCD_STRIDE(w, h) same as STRIDE_MAIN
LCD_FBSTRIDE(w, h) returns target specific stride for a buffer W x H
LCD_NBELEMS(w, h) returns the number of fb_data sized elemenst needed for a buffer W x H
LCD_NATIVE_STRIDE(s) conversion between rockbox native vertical and lcd native stride (2bitH)
test_viewports.c has an example of usage

[FIXED!!] 2bit targets don't respect non-native strides
[FIXED] Few define snags

Change-Id: I0d04c3834e464eca84a5a715743a297a0cefd0af

firmware/target/hosted/sdl/lcd-sdl.c

@@ -39,7 +39,7 @@ void sdl_update_rect(SDL_Surface *surface, int x_start, int y_start, int width,
     (void)max_y;
     (void)getpixel;
     /* Update complete screen via one blit operation (fast) */
-    SDL_Surface *lcd = SDL_CreateRGBSurfaceFrom(lcd_framebuffer, LCD_FBWIDTH,
+    SDL_Surface *lcd = SDL_CreateRGBSurfaceFrom(FBADDR(0, 0), LCD_FBWIDTH,
                                                 LCD_FBHEIGHT, LCD_DEPTH,
                                                 LCD_FBWIDTH * LCD_DEPTH/8,
                                                 0, 0, 0, 0);