bugfix: skip 0'd crc bytes on reply computation

Skip the 0'd CRC bytes on reply computation, mirroring the skipping
during request validation.

Tested: Verified via client the CRC for the reply now matches
expectations.
Change-Id: I18da28604a388fb4210c55f3e54410a067b9f10a
Signed-off-by: Patrick Venture <venture@google.com>
diff --git a/process.cpp b/process.cpp
index 7e6410d..683bf77 100644
--- a/process.cpp
+++ b/process.cpp
@@ -136,9 +136,8 @@
 
     /* The command, whatever it was, replied, so let's set the CRC. */
     crc->clear();
-    replyCmdBuf[0] = 0x00;
-    replyCmdBuf[1] = 0x00;
-    crc->compute(replyCmdBuf, replyLength);
+    crc->compute(replyCmdBuf + sizeof(uint16_t),
+                 replyLength - sizeof(uint16_t));
 
     /* Copy the CRC into place. */
     uint16_t crcValue = crc->get();