EglDisplay may be null and cause Null point exception

Add null check on EglDisplay in case unexpected NPE

Fixes: 139195633
Fixes: 139113237
Test: Run Forest for CTS  x86 CtsAppTestCases on cf_x86_phone-userdebug
Test: atest com.android.systemui.glwallpaper.EglHelperTest

Change-Id: Iefb17082746bacf46b664b253a8baa8ee4b7cd68