Do not block home button if incoming call is a background call

The user want to navigate ahead if it is a call in background.
So we allow it.

Change-Id: If40b8abba05b600191bfc1403f197e624fd7a360
Conflicts:
	policy/src/com/android/internal/policy/impl/PhoneWindowManager.java
PIE: Turn on HWA only if isHighEndGfx()

Signed-off-by: Carlo Savignano <stevewatersy@gmail.com>