pixel3_mainline: device.mk: add lcd_density for Pixel3

Now that lcd_density is made device-specific, add it for Pixel3.

Signed-off-by: Sumit Semwal <sumit.semwal@linaro.org>
Change-Id: Iab08a8b9ea6f8fbc1cdb8d04bc957ef9404e2292
1 file changed