soc: qcom: smd-rpm: Use GFP_ATOMIC in write path

Preparing for better lockdep annotations for things that happen in runpm
suspend/resume path vs shrinker/reclaim in the following patches, we
need to avoid allocations that can trigger reclaim in the icc_set_bw()
path.  In the RPMh case, rpmh_write_batch() already uses GFP_ATOMIC, so
it should be reasonable to use in the smd-rpm case as well.

Alternatively, 256bytes is small enough for a function that isn't called
recursively to allocate on-stack.

Signed-off-by: Rob Clark <robdclark@chromium.org>
Signed-off-by: Bjorn Andersson <andersson@kernel.org>
Link: https://lore.kernel.org/r/20230320144356.803762-21-robdclark@gmail.com