iwlwifi: fix enqueue hcmd race conditions

We mark command as huge by using meta->flags from other (non huge) command,
but flags can be possibly overridden, when non huge command is enqueued,
what can lead to:

WARNING: at lib/dma-debug.c:696 dma_debug_device_change+0x1a3/0x1f0()
DMA-API: device driver has pending DMA allocations while released from device [count=1]

To fix introduce additional CMD_MAPPED to mark command as mapped and
serialize iwl_enqueue_hcmd() with iwl_tx_cmd_complete() using
hcmd_lock. Serialization will also fix possible race conditions,
because q->read_ptr, q->write_ptr are modified/used in parallel.

On the way fix whitespace.

Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/iwlwifi/iwl-dev.h b/drivers/net/wireless/iwlwifi/iwl-dev.h
index a5d438d..7465875 100644
--- a/drivers/net/wireless/iwlwifi/iwl-dev.h
+++ b/drivers/net/wireless/iwlwifi/iwl-dev.h
@@ -309,6 +309,7 @@
 	CMD_SIZE_HUGE = (1 << 0),
 	CMD_ASYNC = (1 << 1),
 	CMD_WANT_SKB = (1 << 2),
+	CMD_MAPPED = (1 << 3),
 };
 
 #define DEF_CMD_PAYLOAD_SIZE 320