udf: fix sparse warnings (shadowing & mismatch between declaration and definition)

fix sparse warnings:
fs/udf/super.c:1431:24: warning: symbol 'bh' shadows an earlier one
fs/udf/super.c:1347:21: originally declared here
fs/udf/super.c:472:6: warning: symbol 'udf_write_super' was not declared. Should it be static?

Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Cc: Ben Fennema <bfennema@falcon.csc.calpoly.edu>
Cc: Jan Kara <jack@suse.cz>
Acked-by: Christoph Hellwig <hch@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/udf/super.c

@@ -474,7 +474,7 @@ static int udf_parse_options(char *options, struct udf_options *uopt)
 	return 1;
 }
 
-void udf_write_super(struct super_block *sb)
+static void udf_write_super(struct super_block *sb)
 {
 	lock_kernel();
 
@@ -1447,7 +1447,6 @@ static int udf_load_partition(struct super_block *sb, kernel_lb_addr *fileset)
 				map->s_type_specific.s_virtual.s_num_entries =
 					(sbi->s_vat_inode->i_size - 36) >> 2;
 			} else if (map->s_partition_type == UDF_VIRTUAL_MAP20) {
-				struct buffer_head *bh = NULL;
 				uint32_t pos;
 
 				pos = udf_block_map(sbi->s_vat_inode, 0);