board/dave/common/flash.c: fix compile warning

Fix warning: ../common/flash.c:668: warning: dereferencing type-punned
pointer will break strict-aliasing rules

Signed-off-by: Wolfgang Denk <wd@denx.de>
Cc: Andrea Marson <andrea.marson@dave-tech.it>

board/dave/common/flash.c

@@ -663,9 +663,10 @@ int write_buff (flash_info_t *info, uchar *src, ulong addr, ulong cnt)
  */
 static int write_word (flash_info_t *info, ulong dest, ulong data)
 {
+	ulong *data_ptr = &data;
 	volatile CONFIG_SYS_FLASH_WORD_SIZE *addr2 = (CONFIG_SYS_FLASH_WORD_SIZE *)(info->start[0]);
 	volatile CONFIG_SYS_FLASH_WORD_SIZE *dest2 = (CONFIG_SYS_FLASH_WORD_SIZE *)dest;
-	volatile CONFIG_SYS_FLASH_WORD_SIZE *data2 = (CONFIG_SYS_FLASH_WORD_SIZE *)&data;
+	volatile CONFIG_SYS_FLASH_WORD_SIZE *data2 = (CONFIG_SYS_FLASH_WORD_SIZE *)data_ptr;
 	ulong start;
 	int flag;
 	int i;