Fix SystemUI wallpaper crash
The issue occurs when the user tries to set as wallpaper an image that
is not srgb. What happens is that variable y value is higher than the
histogram bounds, making sysui crash. One possible fix is to limit y
value to be always less than 256.
Test: Set wallpaper on
https://drive.google.com/file/d/11rxzYvPcIOh_8GvS4XSC3YtbW3CecE-O/viewand check logcat
Change-Id: I8e53bf11ad172ffd786f28c1d74ae0908668b531
Signed-off-by: HrX03 <dn.bianco03@gmail.com>