soc: qcom: rpmhpd: fix sm8350_mxc's peer domain

The sm8350_mxc's domain description incorrectly references
sm8150_mmcx_ao as a peer instead of sm8350_mxc_ao. Correct this typo.

Fixes: 639c8562 ("soc: qcom: rpmhpd: Add SM8350 power domains")
Cc: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20211020012639.1183806-1-dmitry.baryshkov@linaro.org