s/size_t/std::size_t/g - for compatibility with other builds

For compatibility with the Google3 build system, use std::size_t instead
of gnu size_t.

Change-Id: Ie361de9c507119aa7db93d24b6e199547bd123af
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/lpc_aspeed.cpp b/lpc_aspeed.cpp
index 63147c4..120ac76 100644
--- a/lpc_aspeed.cpp
+++ b/lpc_aspeed.cpp
@@ -31,7 +31,7 @@
 {
 
 std::unique_ptr<LpcMapperInterface>
-    LpcMapperAspeed::createAspeedMapper(size_t regionSize)
+    LpcMapperAspeed::createAspeedMapper(std::size_t regionSize)
 {
     /* NOTE: considered using a joint factory to create one or the other, for
      * now, separate factories.