viewports, set flags to VP_DEFAULT_FLAGS

flags were getting un-initialized memory
it really didn't matter with the flags getting initialized
anyway
But once I added a new flag that didn't explicitly
set or clear the flag at init well here we are

set flags to VP_DEFAULT_FLAGS in viewport_set_defaults()

add the flags variable to the default vp's set to 0
(it was already initialized to 0 by bss, make it explicit)

Change-Id: I3a9a062455b4cf66d2b8c70fdf05402a5c0c091c

firmware/drivers/lcd-color-common.c

@@ -61,6 +61,7 @@ static struct viewport default_vp =
     .y        = 0,
     .width    = LCD_WIDTH,
     .height   = LCD_HEIGHT,
+    .flags    = 0,
     .font     = FONT_SYSFIXED,
     .drawmode = DRMODE_SOLID,
     .buffer   = NULL,