dt-bindings: power: qcom,rpmpd: Add SC8280XP_MXC_AO

Not sure how useful it's gonna be in practice, but the definition is
missing (unlike the previously-unused SC8280XP_MXC-non-_AO), so add it
to allow the driver to create the corresponding pmdomain.

Fixes: dbfb5f94e084 ("dt-bindings: power: rpmpd: Add sc8280xp RPMh power-domains")
Acked-by: Rob Herring (Arm) <[e-mail]>
Signed-off-by: Konrad Dybcio <[e-mail]>
Reviewed-by: Ulf Hansson <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Bjorn Andersson <[e-mail]>

include/dt-bindings/power/qcom,rpmhpd.h

···
 #define SC8280XP_NSP		13
 #define SC8280XP_QPHY		14
 #define SC8280XP_XO		15
+#define SC8280XP_MXC_AO		16
 
 #endif