hal: Update platform config params after parsing each kv pair

Existing code parses platform specific config_params from platform
info xml and sends all kvpairs together at the end of config_params
tag. This limits the functionality as we cannot add multiple entries
with the same key. This is because the last parsed kv pair overwrites
the existing key in the hashMap.

Example: With the following xml entries, operator_info for only sprint
entry gets updated in platform data.
<config_params>
    <param key="operator_info" value="tmus;aa;bb;cc"/>
    <param key="operator_info" value="sprint;xx;yy;zz"/>
    ...
</config_params>

Fix this by setting platform data for config params after parsing each
kv pair instead of sending all params together at the end of tag.

Change-Id: Ic4e08be0c25dc8ce07e1bd0fc0de7c4be0e84960