msm8953-common: Add vendor prefix to yet another prop

* Fix network breakage after toggling airplane mode

Change-Id: I91fc2a3f879b075970a75a2a5133f385f855186e

prop.mk

@@ -165,7 +165,7 @@ persist.dbg.ims_volte_enable=1 \
 persist.dbg.volte_avail_ovr=1 \
 persist.dbg.vt_avail_ovr=1 \
 persist.dbg.wfc_avail_ovr=0 \
-persist.radio.apm_sim_not_pwdn=1 \
+persist.vendor.radio.apm_sim_not_pwdn=1 \
 persist.radio.calls.on.ims=0 \
 persist.radio.csvt.enabled=false \
 persist.radio.hw_mbn_update=0 \