msm: rndis_ipa: continue rndis cleanup although header removal failed

On USB dynamic composition switch, rndis cleanup procedure is called.
Sporadically, it could be called from adb context while adbd
process is being killed. DMA memory allocation fails due to inappropriate
state of adbd process.

rndis cleanup allocates dma memory in order to remove rndis headers
to IPA core.
Consequently, cleanup will fail and usb tethering will remain turned on.

The solution is to proceed with the cleanup although the dma memory
allocation fails.

CRs-fixed: 764915
Change-Id: I0429fa5163368fc909134e3c3152aa5b90b08b4b
Signed-off-by: Ghanim Fodi <gfodi@codeaurora.org>