Restructure vr_ui

Get rid of pixel offset variables, and use makefile variables in
BoardConfigs.

Bug: 37779982
Test: Verified vr ui has same behavior.
Change-Id: Ifbf44e27d7101aedbe3c0e6db4b8181d56efadfd

screen_ui.cpp

@@ -336,7 +336,7 @@ void ScreenRecoveryUI::draw_screen_locked() {
   SetColor(LOG);
   int row = (text_top_ + text_rows_ - 1) % text_rows_;
   size_t count = 0;
-  for (int ty = gr_fb_height() - kMarginHeight - char_height_ - log_bottom_offset_;
+  for (int ty = gr_fb_height() - kMarginHeight - char_height_;
        ty >= y && count < text_rows_; ty -= char_height_, ++count) {
     int temp_y = ty;
     DrawTextLine(x, &temp_y, text_[row], false);
@@ -459,7 +459,6 @@ bool ScreenRecoveryUI::InitTextParams() {
   gr_font_size(gr_sys_font(), &char_width_, &char_height_);
   text_rows_ = (gr_fb_height() - kMarginHeight * 2) / char_height_;
   text_cols_ = (gr_fb_width() - kMarginWidth * 2) / char_width_;
-  log_bottom_offset_ = 0;
   return true;
 }