dtc: pos parameter to srcpos_string() can't be NULL

None of the callers ever pass a NULL to srcpos_string(), so the check
for it is not necessary.  Furthermore, checking it make Coverity complain
about the raw dereferences which follow later in the function.

Signed-off-by: David Gibson <[email protected]>
diff --git a/srcpos.c b/srcpos.c
index aa3aad0..9d38459 100644
--- a/srcpos.c
+++ b/srcpos.c
@@ -252,7 +252,7 @@
 	const char *fname = "<no-file>";
 	char *pos_str;
 
-	if (pos)
+	if (pos->file && pos->file->name)
 		fname = pos->file->name;