msm_bam_rmnet: Fix packet corruption due to QoS

Remove the QoS header added at the beginning of the
SKB (If QoS is enabled) in case of a failure to send
a packet to bam_dmux in order to avoid a possible loop
that adds QoS headers on each failure which will cause
a packet corruption.

Change-Id: I5cda4db1f49638b37998d2502ff07b1e82518db1
Acked-by: David Arinzon <darinzon@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>