xfs: fix the xfs_log_iovec i_addr type

By making this member a void pointer we can get rid of a lot of pointless
casts.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>

diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c
index 1857c41..f461760 100644
--- a/fs/xfs/xfs_log.c
+++ b/fs/xfs/xfs_log.c
@@ -548,7 +548,7 @@
 				.magic = XLOG_UNMOUNT_TYPE,
 			};
 			struct xfs_log_iovec reg = {
-				.i_addr = (void *)&magic,
+				.i_addr = &magic,
 				.i_len = sizeof(magic),
 				.i_type = XLOG_REG_TYPE_UNMOUNT,
 			};