lineage: Manually include gsi_release.mk for generic lineage targets

* AOSP wrapped these around aosp_{arm,arm64,x86,x86_64} checks
  thus we need to have them here instead.

Change-Id: Ia3e1e37361330c4b28759f07a3fef6c78565e958

build/target/product/lineage_generic_target.mk

@@ -12,6 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
+$(call inherit-product, build/target/product/gsi_release.mk)
 $(call inherit-product, vendor/lineage/config/common_mobile.mk)
 
 PRODUCT_COPY_FILES += \