kernel: Fix vdso32 building for 4.19+ kernels

This flag has been renamed in 4.19 kernels
https://android.googlesource.com/kernel/common/+/refs/heads/android-4.19-stable/arch/arm64/kernel/vdso32/Makefile#13

Change-Id: I92db29aa124da7c9fc63454d9443373bdc2e16e7
1 file changed