Add context for ro.boot.product.hardware.sku.

This was defined, but it had no users in the Android tree.
Because of this, ODM manifests required extra sepolicy to be applied
in vendor. Before this, there was no policy split, so that was okay,
but now it is impossible.

Bug: 91735839
Test: add an odm manifest for SE conditional on
    a system property (ro.boot.product.hardware.sku)
    and make sure it is read into the manifest (using
    the vintf tool) and also that a client can get the
$ lshal | grep secure
Y android.hardware.secure_element@1.0::ISecureElement/SIM1                                  0/2        881    2262 567

Change-Id: I94a2928943be6a17416b8bbd78106809c0c21198
Merged-In: I94a2928943be6a17416b8bbd78106809c0c21198