powerpc/BSR: Make use of the helper macro LIST_HEAD()

Replace "struct list_head head = LIST_HEAD_INIT(head)" with
"LIST_HEAD(head)" to simplify the code.
Signed-off-by: NCai Huoqing <cai.huoqing@linux.dev>
Link: https://lore.kernel.org/r/20220209032450.37849-1-cai.huoqing@linux.devSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/char/bsr.c

@@ -60,7 +60,7 @@ struct bsr_dev {
 };
 
 static unsigned total_bsr_devs;
-static struct list_head bsr_devs = LIST_HEAD_INIT(bsr_devs);
+static LIST_HEAD(bsr_devs);
 static struct class *bsr_class;
 static int bsr_major;