Correct bp2build canonical_from_root logic

The logic was inverted from what it should have been,
canonical_from_root --> no strip_import_prefix attribute.

Test: build/bazel/ci/bp2build.sh
Test: build/bazel/ci/mixed_droid.sh
Change-Id: Ic6685d8f0b88279d4444bab3b5e03a544d225f77
diff --git a/android/proto.go b/android/proto.go
index 64d4d05..f466261 100644
--- a/android/proto.go
+++ b/android/proto.go
@@ -187,7 +187,7 @@
 			if axis == bazel.NoConfigAxis {
 				info.Type = props.Proto.Type
 
-				if proptools.BoolDefault(props.Proto.Canonical_path_from_root, canonicalPathFromRootDefault) {
+				if !proptools.BoolDefault(props.Proto.Canonical_path_from_root, canonicalPathFromRootDefault) {
 					// an empty string indicates to strips the package path
 					path := ""
 					attrs.Strip_import_prefix = &path