Fix some special usb can't mount issue.

[Description]
The usb has invalid partition table, but vold thinks it has partition.
So vold not to treat entire disk as partition.

Bug: 160433451

[Test Report]
Build pass.
The special usb can mount ok.

Change-Id: I0b0e761641f6961e69d7d7f7fbc58d33eeab3a08
diff --git a/model/Disk.cpp b/model/Disk.cpp
index 4df4e9d..01cd0c3 100644
--- a/model/Disk.cpp
+++ b/model/Disk.cpp
@@ -365,7 +365,6 @@
                 continue;
             }
         } else if (*it == "PART") {
-            foundParts = true;
 
             if (++it == split.end()) continue;
             int i = 0;
@@ -390,6 +389,7 @@
                     case 0x0c:  // W95 FAT32 (LBA)
                     case 0x0e:  // W95 FAT16 (LBA)
                         createPublicVolume(partDevice);
+                        foundParts = true;
                         break;
                 }
             } else if (table == Table::kGpt) {
@@ -400,8 +400,10 @@
 
                 if (android::base::EqualsIgnoreCase(typeGuid, kGptBasicData)) {
                     createPublicVolume(partDevice);
+                    foundParts = true;
                 } else if (android::base::EqualsIgnoreCase(typeGuid, kGptAndroidExpand)) {
                     createPrivateVolume(partDevice, partGuid);
+                    foundParts = true;
                 }
             }
         }