arm/dt: msm9625: Remove qcom,allow-atomic regulator property for S2

No consumers require atomic access for PM8019 regulator SMPS 2.
Therefore, remove the qcom,allow-atomic property for this
regulator so that additional latency is not introduced during
SMPS 2 transactions.

Change-Id: If4539b5d1750013922f8fac8e85815412f91b225
Signed-off-by: David Collins <collinsd@codeaurora.org>