Add property value to indicate support for dual SIM mode.

Add system property to differentiate devices that support enablement of
dual SIM mode from those that don't, even if they have two or more SIM
cards.

Bug: 123537730
Test: Compilation, test application
Change-Id: I6b25b778fcac40b4f7d2faa1de11f3c84ac040eb
Signed-off-by: ronaxdevil <pratabidya.007@gmail.com>

vendor_prop.mk

@@ -269,6 +269,7 @@ PRODUCT_PROPERTY_OVERRIDES += \
     persist.vendor.radio.is_wps_enabled=true \
     persist.vendor.radio.mt_sms_ack=30 \
     persist.vendor.radio.0x9e_not_callname=1 \
+    persist.vendor.radio.multisim_switch_support=true \
     persist.vendor.radio.qcril_uim_vcc_feature=1 \
     persist.mot.gps.conf.from.sim=true \
     persist.net.doxlat=true \