[MIPS] Fix warning about unused definition in c-sb1.c

arch/mips/mm/c-sb1.c: In function `sb1_cache_init':
arch/mips/mm/c-sb1.c:447: warning: unused variable `handle_vec2_sb1'
Signed-off-by: NYoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/mm/c-sb1.c

@@ -444,7 +444,6 @@ static __init void probe_cache_sizes(void)
 void sb1_cache_init(void)
 {
 	extern char except_vec2_sb1;
-	extern char handle_vec2_sb1;
 
 	/* Special cache error handler for SB1 */
 	set_uncached_handler (0x100, &except_vec2_sb1, 0x80);