net: Break out nested function

net: Break out nested function

Nested functions are not supported in C, but are permitted as an extension
in the GNU C dialect. Commit cb2f15c5448 ("normal/main: Search for specific
config files for netboot") added a nested function which caused the build
to break when compiling with clang.

Break that out into a static helper function to make the code portable again.

Reported-by: Daniel Axtens <dja@axtens.net>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Tested-by: Daniel Axtens <dja@axtens.net>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>