UPSTREAM: exfat: fix potential wrong error return from get_block

If there is no error, get_block() should return 0. However, when bh_read()
returns 1, get_block() also returns 1 in the same manner.

Let's set err to 0, if there is no error from bh_read()

Fixes: 11a347fb ("exfat: change to get file size from DataLength")
Cc: stable@vger.kernel.org
Signed-off-by: Sungjong Seo <sj1557.seo@samsung.com>
Reviewed-by: Yuezhang Mo <Yuezhang.Mo@sony.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>

(cherry-picked from commit 59c30e31)
Change-Id: I808c5879bb75c71652a8a635339c3119d614dd88
Bug: 412215407
Signed-off-by: Paul Lawrence <paullawrence@google.com>
(cherry picked from commit b41dff1d)
Signed-off-by: Lee Jones <joneslee@google.com>