[U-Boot] [RFC] disk: part_dos: Fix part_test_dos() regression

[Fabio Estevam <festevam@gmail.com>]

From: Fabio Estevam <fabio.estevam@nxp.com>

Since commit ff98cb90514d ("part: extract MBR signature from partitions")
SPL boot on i.MX6 starts to fail:

U-Boot SPL 2017.09-00221-g0d6ab32 (Oct 02 2017 - 15:13:19)
Trying to boot from MMC1
(hangs here)

Revert the part_test_dos() changes from this commit, so that
SPL boot can be functional again.

Tested on a imx6q-cuboxi board.

Signed-off-by: Fabio Estevam <fabio.estevam@nxp.com>
---
 disk/part_dos.c | 10 ++--------
 1 file changed, 2 insertions(+), 8 deletions(-)

diff --git a/disk/part_dos.c b/disk/part_dos.c
index 1a36be0..213a8d8 100644
--- a/disk/part_dos.c
+++ b/disk/part_dos.c
@@ -89,20 +89,14 @@ static int test_block_type(unsigned char *buffer)
 
 static int part_test_dos(struct blk_desc *dev_desc)
 {
-	ALLOC_CACHE_ALIGN_BUFFER(legacy_mbr, mbr, dev_desc->blksz);
+	ALLOC_CACHE_ALIGN_BUFFER(unsigned char, mbr, dev_desc->blksz);
 
 	if (blk_dread(dev_desc, 0, 1, (ulong *)mbr) != 1)
 		return -1;
 
-	if (test_block_type((unsigned char *)mbr) != DOS_MBR)
+	if (test_block_type(mbr) != DOS_MBR)
 		return -1;
 
-	if (dev_desc->sig_type == SIG_TYPE_NONE &&
-	    mbr->unique_mbr_signature != 0) {
-		dev_desc->sig_type = SIG_TYPE_MBR;
-		dev_desc->mbr_sig = mbr->unique_mbr_signature;
-	}
-
 	return 0;
 }
 
-- 
2.7.4