net: qualcomm: rmnet: Fix for UL aggregation with stats change

UL aggregation returns -EINPROGRESS so use this information
to skip freeing rather than always freeing and recording tx_drops.

CRs-Fixed: 2226308
Change-Id: I89e39e9d8af5efe7442ee751e0f5d980278c213a
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>