Set 32bits Legacy GSI to be 32bits binder

The binder interface bitness is always 64bits from P.
To keep 32bits binder interface for Legacy GSI, we need to explict
configure it.

Bug: 122282239
Test: lunch aosp_arm_ab-userdebug; make -j
Change-Id: I90b45adb52c398d1c0cf3f877199f9dd1e0b3f86