iommu/arm-smmu-qcom: Add SC7280 SMMU compatible

Add compatible for SC7280 SMMU to use the Qualcomm Technologies, Inc.
specific implementation.

Signed-off-by: Sai Prakash Ranjan <saiprakash.ranjan@codeaurora.org>
Reviewed-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/53a50cd91c97b5b598a73941985b79b51acefa14.1623155117.git.saiprakash.ranjan@codeaurora.org
Signed-off-by: Will Deacon <will@kernel.org>