tools: ynl-gen: don't declare loop iterator in place

The codegen tries to follow the "old" C style and declare loop
iterators at the start of the block / function. Only nested
request handling breaks this style, so adjust it.

Reviewed-by: Donald Hunter <donald.hunter@gmail.com>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20250414211851.602096-2-kuba@kernel.org


Signed-off-by: Jakub Kicinski <kuba@kernel.org>