iommu: Properly export iommu_group_get_for_dev()

mainline inclusion
from mainline-v5.7-rc4
commit ae74c19f
category: bugfix
bugzilla: 34842, https://gitee.com/openeuler/kernel/issues/I6H9U5
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=ae74c19faa7d7996e857e13165bd40fc4a285e0d



--------------------------------

In commit a7ba5c3d ("drivers/iommu: Export core IOMMU API symbols to
permit modular drivers") a bunch of iommu symbols were exported, all
with _GPL markings except iommu_group_get_for_dev().  That export should
also be _GPL like the others.

Fixes: a7ba5c3d ("drivers/iommu: Export core IOMMU API symbols to permit modular drivers")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Will Deacon <will@kernel.org>
Cc: Joerg Roedel <jroedel@suse.de>
Cc: John Garry <john.garry@huawei.com>
Cc: Will Deacon <will@kernel.org>
Link: https://lore.kernel.org/r/20200430120120.2948448-1-gregkh@linuxfoundation.org


Signed-off-by: Joerg Roedel <jroedel@suse.de>
Signed-off-by: Guo Mengqi <guomengqi3@huawei.com>
Reviewed-by: Weilong Chen <chenweilong@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>