Result of read() is signed

Change-Id: I6f849d5fe0ac103b571171d462052d9de6817ff1
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
diff --git a/sbe_chipOp_handler.cpp b/sbe_chipOp_handler.cpp
index b285e9a..81a24b0 100644
--- a/sbe_chipOp_handler.cpp
+++ b/sbe_chipOp_handler.cpp
@@ -26,7 +26,7 @@
                                     size_t cmdBufLen,
                                     size_t respBufLen)
 {
-    size_t len = 0;
+    ssize_t len = 0;
     std::vector<sbe_word_t> response;
     std::ostringstream errMsg;
 
@@ -84,7 +84,7 @@
     //Create a temporary buffer
     std::vector<sbe_word_t> buffer(totalReadLen);
 
-    auto bytesToRead = (totalReadLen * WORD_SIZE);
+    ssize_t bytesToRead = (totalReadLen * WORD_SIZE);
     len = read(fileFd(), buffer.data(), bytesToRead);
     if (len < 0)
     {