Increase size of RAM on microdroid x86_64

Due to u-boot change r.android.com/1825892, the volume of RAM needed has
increased by 128 MB. Increase the RAM allocated for microdroid
appropriately.

Bug: 198436511
Bug: 155019925
Test: atest MicrodroidHostTestCases:android.virt.test.MicrodroidTestCase
Change-Id: Ic8b3ec9a46625174c532767f9668a2830d969180
diff --git a/tests/hostside/java/android/virt/test/MicrodroidTestCase.java b/tests/hostside/java/android/virt/test/MicrodroidTestCase.java
index 6548428..91b33a3 100644
--- a/tests/hostside/java/android/virt/test/MicrodroidTestCase.java
+++ b/tests/hostside/java/android/virt/test/MicrodroidTestCase.java
@@ -35,7 +35,7 @@
     private static final String PACKAGE_NAME = "com.android.microdroid.test";
 
     private static final int MIN_MEM_ARM64 = 125;
-    private static final int MIN_MEM_X86_64 = 270;
+    private static final int MIN_MEM_X86_64 = 400;
 
     private int minMemorySize() throws DeviceNotAvailableException {
         CommandRunner android = new CommandRunner(getDevice());