Fix bridge FALLTHROUGH annotation

[andy31415]

Make linux-arm64-dynamic-bridge-ipv6only-clang compile again after #25854.

[github-actions]

PR #25870: Size comparison from 040c65d to 584e6ee

Full report (1 build for cc32xx)

platform	target	config	section	040c65d	584e6ee	change	% change
cc32xx	lock	CC3235SF_LAUNCHXL		0	0	0	0.0
			(read only)	645745	645745	0	0.0
			(read/write)	203848	203848	0	0.0
			.ARM.attributes	44	44	0	0.0
			.ARM.exidx	8	8	0	0.0
			.bss	197248	197248	0	0.0
			.comment	194	194	0	0.0
			.data	1480	1480	0	0.0
			.debug_abbrev	933102	933102	0	0.0
			.debug_aranges	87704	87704	0	0.0
			.debug_frame	301604	301604	0	0.0
			.debug_info	20309906	20309906	0	0.0
			.debug_line	2680953	2680953	0	0.0
			.debug_loc	2827596	2827596	0	0.0
			.debug_ranges	286376	286376	0	0.0
			.debug_str	3041114	3041114	0	0.0
			.ramVecs	780	780	0	0.0
			.resetVecs	64	64	0	0.0
			.rodata	105953	105953	0	0.0
			.shstrtab	232	232	0	0.0
			.stab	204	204	0	0.0
			.stabstr	441	441	0	0.0
			.stack	2048	2048	0	0.0
			.strtab	380555	380555	0	0.0
			.symtab	257456	257456	0	0.0
			.text	537672	537672	0	0.0