powerpc/pmac: remove unused symbol

sccdbg symbol is not used, so remove it
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zucheng Zheng <zhengzucheng@huawei.com>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210409093519.118000-1-zhengzucheng@huawei.com

arch/powerpc/platforms/powermac/setup.c

@@ -81,10 +81,6 @@ static int current_root_goodness = -1;
 
 #define DEFAULT_ROOT_DEVICE Root_SDA1	/* sda1 - slightly silly choice */
 
-#ifdef CONFIG_PPC64
-int sccdbg;
-#endif
-
 sys_ctrler_t sys_ctrler = SYS_CTRLER_UNKNOWN;
 EXPORT_SYMBOL(sys_ctrler);