trusty: Remove redundant check

This repeats a check in the lines immediately before it.

Test: TreeHugger
Change-Id: I47ac9f359018b87bc283657eddb75ad3d175244e
diff --git a/trusty/confirmationui/TrustyApp.cpp b/trusty/confirmationui/TrustyApp.cpp
index 0e84b19..1e70a5e 100644
--- a/trusty/confirmationui/TrustyApp.cpp
+++ b/trusty/confirmationui/TrustyApp.cpp
@@ -107,11 +107,6 @@
         return;
     }
 
-    if (dma_buf < 0) {
-        LOG(ERROR) << AT << "failed to allocate shared memory buffer";
-        return;
-    }
-
     confirmationui_hdr hdr = {
         .cmd = CONFIRMATIONUI_CMD_INIT,
     };