udf: initialize newblock to 0

The clang build reports this error
fs/udf/inode.c:805:6: error: variable 'newblock' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
        if (*err < 0)
            ^~~~~~~~
newblock is never set before error handling jump.
Initialize newblock to 0 and remove redundant settings.

Fixes: d8b39db ("udf: Handle error when adding extent to a file")
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20221230175341.1629734-1-trix@redhat.com>

Author: Tom Rix

fs/udf/inode.c

@@ -684,7 +684,7 @@ static sector_t inode_getblk(struct inode *inode, sector_t block,
 	struct kernel_lb_addr eloc, tmpeloc;
 	int c = 1;
 	loff_t lbcount = 0, b_off = 0;
-	udf_pblk_t newblocknum, newblock;
+	udf_pblk_t newblocknum, newblock = 0;
 	sector_t offset = 0;
 	int8_t etype;
 	struct udf_inode_info *iinfo = UDF_I(inode);
@@ -787,7 +787,6 @@ static sector_t inode_getblk(struct inode *inode, sector_t block,
 		ret = udf_do_extend_file(inode, &prev_epos, laarr, hole_len);
 		if (ret < 0) {
 			*err = ret;
-			newblock = 0;
 			goto out_free;
 		}
 		c = 0;
@@ -852,7 +851,6 @@ static sector_t inode_getblk(struct inode *inode, sector_t block,
 				goal, err);
 		if (!newblocknum) {
 			*err = -ENOSPC;
-			newblock = 0;
 			goto out_free;
 		}
 		if (isBeyondEOF)