gen_syscalls.py: do not output data to stdout

There's no particularly good reason to have one kind of
output from this script to be sent to stdout instead of
a filename specified by parameter, and it makes it
annoying to add debug print() statements.

Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 57ae22d..c721de0 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -455,7 +455,7 @@
   --json-file        ${syscalls_json}                     # Read this file
   --base-output      include/generated/syscalls           # Write to this dir
   --syscall-dispatch include/generated/syscall_dispatch.c # Write this file
-  > ${syscall_list_h}                                     # Write stdout to this file
+  --syscall-list     ${syscall_list_h}
   WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
   DEPENDS ${syscalls_json}
   )