Keep display density constant

Currently Android assumes that display density is constant for
all display modes (and displays), however applying config_maxUiWidth
recalculates the density, which makes ro.sf.lcd_density impossible
to adjust on devices which can be connected to different displays.

Test: build and flash
Bug: 159310126
Bug: 156100799
Change-Id: I2dbee9f54f46c7b8b1857b2d8d8dc3b90585faa2