scripts: kernel-doc: remove unnecessary change wrt Linux

A comment in kernel-doc mentions QEMU's qatomic_set macro, but since
this code originated in Linux we should just revert it and stay as close
to the kernel's copy of the script as possible.

The change was introduced (more or less unintentionally) in QEMU commit
commit d73415a315, which did a global search-and-replace of QEMU's
atomic access macros.

Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

scripts/kernel-doc

@@ -1758,7 +1758,7 @@ sub dump_function($$) {
     # If you mess with these regexps, it's a good idea to check that
     # the following functions' documentation still comes out right:
     # - parport_register_device (function pointer parameters)
-    # - qatomic_set (macro)
+    # - atomic_set (macro)
     # - pci_match_device, __copy_to_user (long return type)
 
     if ($define && $prototype =~ m/^()([a-zA-Z0-9_~:]+)\s+/) {