llstats: Use mNumRadioAllocated for real radio stats recevied

Wifihal uses mNumRadio from QCA_WLAN_VENDOR_ATTR_LL_STATS_NUM_RADIOS,
but it shall use mNumRadioAllocated which is based on the real radio
stats received.

This avoids memory out-of-bound access.

CRs-Fixed: 2863682
Change-Id: Ia1c8484307182a3fab8fbfbde2a9be9047eade61