qcacmn: Fix -Wmissing-prototypes in dp_tx.c

We want to enable the compiler's -Wmissing-prototypes switch, but
there is existing code in dp_tx.c that is generating warnings.  Fix
these warnings by making the following functions static:
	dp_tx_desc_release()
	dp_tx_prepare_htt_metadata()
	dp_tx_prepare_ext_desc()
	dp_tx_prepare_desc_single()
	dp_tx_prepare_desc()
	dp_tx_prepare_raw()
	dp_tx_hw_enqueue()
	dp_tx_classify_tid()
	dp_tx_send_msdu_single()
	dp_tx_send_msdu_multiple()
	dp_tx_prepare_sg()
	dp_tx_reinject_handler()
	dp_tx_inspect_handler()
	dp_tx_process_htt_completion()
	dp_tx_comp_process_desc()

Change-Id: I4d40b836af85ea3c3dbee0c11514e2c1d2e9c8cb
CRs-Fixed: 1108175
1 file changed