BACKPORT: UPSTREAM: ath10k: enable hw checksum for wcn3990

By default ath10k driver enables the support for HW_CHECKSUM
(NETIF_F_HW_CSUM). Since the TCP/UDP checksum calculation is not enabled
in the wcn3990 firmware the checksum is incorrect in the TCP/UDP packets
and all patckets are dropped. But due note that wcn3990 support in
ath10k is still incomplete so this isn't a critical fix (yet).

Enable hw checksum calculations in wcn3990 hardware by
setting the proper flags in msdu descriptor tso flags.

Signed-off-by: Rakesh Pillai <pillair@codeaurora.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
[dundi@codeaurora.org: resolve trivial merge conflicts in
drivers/net/wireless/ath/ath10k/htt_tx.c]
Git-commit: 20529b33aa12224e4399b4486e5ab617cf8f3e5e
Git-repo: git://git.kernel.org/pub/scm/linux/kernel/git/kvalo/ath.git


Change-Id: I2934a6d695826c604007c550159811ee2e9943e8
Signed-off-by: Dundi Raviteja <dundi@codeaurora.org>