AVRCP TG: Get Item Attribute command not working

Usecase:
1) Connect from carkit supporting AVRCP 1.4/1.5 CT to DUT
2) Issue get item attribute command with valid attribute list.

Expected behaviour:
Get item attribute command succeeds and returns the requested
attributes of particular item

Observed result:
Get Item attribute command fails with BAD Param Error

Root Cause:
Wrong structure from tAVRC_COMMAND was being passed to fill_attribute_id_array
which was leading to error being returned.

Fix:
Use get_attrs of type tAVRC_GET_ATTRS_CMD instead of get_elem_attrs of type
tAVRC_GET_ELEM_ATTRS_CMD when remote device requests for get item attributes.

Test: Checked that now bad param error is not returned in response for
get item attribute command from remote device.

Bug: 37302234
Change-Id: I9245f726f37ffd666d143d2232dac868a2cc3268