inet: frags: eliminate kernel-doc warning

inet: frags: eliminate kernel-doc warning

Modify the anonymous enum kernel-doc content so that it doesn't cause
a kernel-doc warning.

inet_frag.h:33: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst

Fixes: 1ab1934ed80a ("inet: frags: enum the flag definitions and add descriptions")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Nikolay Aleksandrov <razor@blackwall.org>
Link: https://lore.kernel.org/r/20230714045127.18752-6-rdunlap@infradead.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>