PATI board: fix compiler warnings

Fix these:
pati.c: In function 'checkboard':
pati.c:358: warning: pointer targets in passing argument 2 of 'getenv_r' differ in signedness
../common/flash.c: In function 'write_word':
../common/flash.c:824: warning: dereferencing type-punned pointer will break strict-aliasing rules
cmd_pati.c: In function 'do_pati':
cmd_pati.c:279: warning: 'value' may be used uninitialized in this function

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/board/mpl/common/flash.c b/board/mpl/common/flash.c
index 302d7a3..355608c 100644
--- a/board/mpl/common/flash.c
+++ b/board/mpl/common/flash.c
@@ -819,13 +819,17 @@
 
 static int write_word (flash_info_t *info, ulong dest, ulong data)
 {
-	volatile FLASH_WORD_SIZE *addr2 = (FLASH_WORD_SIZE *)(info->start[0]);
-	volatile FLASH_WORD_SIZE *dest2 = (FLASH_WORD_SIZE *)dest;
-	volatile FLASH_WORD_SIZE *data2 = (FLASH_WORD_SIZE *)&data;
+	volatile FLASH_WORD_SIZE *addr2 = (volatile FLASH_WORD_SIZE *)(info->start[0]);
+	volatile FLASH_WORD_SIZE *dest2 = (volatile FLASH_WORD_SIZE *)dest;
+	volatile FLASH_WORD_SIZE *data2;
 	ulong start;
+	ulong *data_p;
 	int flag;
 	int i;
 
+	data_p = &data;
+	data2 = (volatile FLASH_WORD_SIZE *)data_p;
+
 	/* Check if Flash is (sufficiently) erased */
 	if ((*((volatile FLASH_WORD_SIZE *)dest) &
 		(FLASH_WORD_SIZE)data) != (FLASH_WORD_SIZE)data) {