mailbox: bcm-ferxrm-mailbox: Fix error check for dma_map_sg

stable inclusion
from stable-v5.10.150
commit 44c26ceffaa39029336f83010978f380767b2620
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I6D0XA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=44c26ceffaa39029336f83010978f380767b2620



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[ Upstream commit 6b207ce8 ]

dma_map_sg return 0 on error, fix the error check, and return -EIO
to caller.

Fixes: dbc049ee ("mailbox: Add driver for Broadcom FlexRM ring manager")
Signed-off-by: Jack Wang <jinpu.wang@ionos.com>
Signed-off-by: Jassi Brar <jaswinder.singh@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jialin Zhang <zhangjialin11@huawei.com>