qcacmn: Remove csum_enabled flag check

Currently, to set checksum enable flags in Tx descriptor
we are checking the csum_enabled flag along with stack checksum
offload request. In case of roaming from latency-critical connection
to non-latency critical connection we request stack to calculate
checksum and set csum_enabled flag to 0. For some packets which
are already queued where the stack has not calculated checksum and
csum_enabled flag is set to 0, we will not set the checksum enable
flags in Tx descriptors for those packets.

To fix the issue remove the csum_enabled flag check and directly
check if the stack has calculated checksum for those packets or not.

Change-Id: I8d7754afc3d0a33315b85b0113cd3062e5783e28
CRs-Fixed: 3070858