net: moxa: fix endianness-related issues from 'sparse'

Sparse checker found two endianness-related issues:

.../moxart_ether.c:34:15: warning: incorrect type in assignment (different base types)
.../moxart_ether.c:34:15:    expected unsigned int [usertype]
.../moxart_ether.c:34:15:    got restricted __le32 [usertype]

.../moxart_ether.c:39:16: warning: cast to restricted __le32

Fix them by using __le32 type instead of u32.
Signed-off-by: Sergei Antonov <saproj@gmail.com>
Link: https://lore.kernel.org/r/20220902125037.1480268-1-saproj@gmail.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/ethernet/moxa/moxart_ether.c

@@ -29,12 +29,12 @@
 
 #include "moxart_ether.h"
 
-static inline void moxart_desc_write(u32 data, u32 *desc)
+static inline void moxart_desc_write(u32 data, __le32 *desc)
 {
 	*desc = cpu_to_le32(data);
 }
 
-static inline u32 moxart_desc_read(u32 *desc)
+static inline u32 moxart_desc_read(__le32 *desc)
 {
 	return le32_to_cpu(*desc);
 }