UPSTREAM: iommu/rockchip: Fix zap cache during device attach

UPSTREAM: iommu/rockchip: Fix zap cache during device attach

rk_iommu_command() takes a struct rk_iommu and iterates over the slave
MMUs, so this is doubly wrong in that we're passing in the wrong pointer
and talking to MMUs that we shouldn't be.

Fixes: cd6438c5f844 ("iommu/rockchip: Reconstruct to support multi slaves")
Cc: stable@vger.kernel.org
Signed-off-by: John Keeping <john@metanate.com>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Joerg Roedel <jroedel@suse.de>
(cherry picked from commit ae8a7910fb0568531033bd6ebe65590f7a4fa6e2)

Change-Id: I5d6f5dd49ad0f79facee8d345c5058af80226f83
Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>