qcacld-2.0: Add lost AP sample size entry to nla policy

Incorrect validation of
QCA_WLAN_VENDOR_ATTR_EXTSCAN_BSSID_HOTLIST_PARAMS_LOST_AP_SAMPLE_SIZE
results in assigning an unchecked user-controller value.
This can lead to buffer overflow.

validate 
  QCA_WLAN_VENDOR_ATTR_EXTSCAN_BSSID_HOTLIST_PARAMS_LOST_AP_SAMPLE_SIZE.

CRs-Fixed: 2045470
Change-Id: I7c33b6d78054672e9effbe9100c29e5604c250c6
Bug: 36818198
Signed-off-by: Srinivas Girigowda <sgirigow@codeaurora.org>