Fix: required deps from native module to phony module is respected

This change fixes a bug that required deps from native module to phony
module was ignored. It happened because addRequireDeps incorrectly
thought that both are native modules with different bitness (32->64),
which isn't.

Fix this by doing the bitness check only when both the current module
and the required module are native modules.

Bug: N/A
Test: go test ./... under build/soong/filesystem
Change-Id: I494ebc47e29001f174fa44d72809041f8ceffb0b