ASoC: dt-bindings: Fix description for msm8916

For the existing msm8916 bindings the minimum reg/reg-names is 1 not 2.
Similarly the minimum interrupt/interrupt-names is 1 not 2.

Fixes: f3fc4fbf ("ASoC: dt-bindings: Add SC7280 lpass cpu bindings")
Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>