netcp: try to reduce type confusion in descriptors

The netcp driver produces tons of warnings when CONFIG_LPAE is enabled
on ARM:

drivers/net/ethernet/ti/netcp_core.c: In function 'netcp_tx_map_skb':
drivers/net/ethernet/ti/netcp_core.c:1084:13: warning: passing argument 1 of 'set_words' from incompatible pointer type [-Wincompatible-pointer-types]

This is the result of trying to pass a pointer to a dma_addr_t to
a function that expects a u32 pointer to copy that into a DMA descriptor.

Looking at that code in more detail to fix the warnings, I see multiple
related problems:

* The conversion functions are not endian-safe, as the DMA descriptors
  are almost certainly fixed-endian, but the CPU is not.

* On 64-bit machines, passing a pointer through a u32 variable is a
  bug, accessing an indirect pointer as a u32 pointer even more so.

* The handling of epib and psdata mixes native-endian and device-endian
  data.

In this patch, I try to sort out the types for most accesses here,
adding le32_to_cpu/cpu_to_le32 where appropriate, and passing pointers
through two 32-bit words in the descriptor padding, to make it plausible
that the driver does the right thing if compiled for big-endian or
64-bit systems.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/linux/soc/ti/knav_dma.h

@@ -144,17 +144,17 @@ struct knav_dma_cfg {
  * @psdata:			Protocol specific
  */
 struct knav_dma_desc {
-	u32	desc_info;
-	u32	tag_info;
-	u32	packet_info;
-	u32	buff_len;
-	u32	buff;
-	u32	next_desc;
-	u32	orig_len;
-	u32	orig_buff;
-	u32	epib[KNAV_DMA_NUM_EPIB_WORDS];
-	u32	psdata[KNAV_DMA_NUM_PS_WORDS];
-	u32	pad[4];
+	__le32	desc_info;
+	__le32	tag_info;
+	__le32	packet_info;
+	__le32	buff_len;
+	__le32	buff;
+	__le32	next_desc;
+	__le32	orig_len;
+	__le32	orig_buff;
+	__le32	epib[KNAV_DMA_NUM_EPIB_WORDS];
+	__le32	psdata[KNAV_DMA_NUM_PS_WORDS];
+	__le32	pad[4];
 } ____cacheline_aligned;
 
 #if IS_ENABLED(CONFIG_KEYSTONE_NAVIGATOR_DMA)