Fix the font size selection for recovery mode

shamu has a 560dpi density, which is between xxhdpi and xxxhdpi. It
deserves the large font (18x32), otherwise it falls back to use the
small one and makes it mostly unreadable under recovery mode. Amend
the list to include 560dpi and 400dpi that are higher than xhdpi.
Ideally we should map string formats back to numbers for easy
comparison (and to handle any high but odd density values).

Change-Id: Ie08d9ce5e1c8850ff30a79bcbfd1b89e971b7e07