FAT32: fix support for superfloppy-format (PBR)

"Superfloppy" format (in U-Boot called PBR) did not work for FAT32 as
the file system type string is at a different location. Add support
for FAT32.

Signed-off-by: Wolfgang Denk <wd@denx.de>
diff --git a/disk/part_dos.c b/disk/part_dos.c
index 887b75e..2de1bb8 100644
--- a/disk/part_dos.c
+++ b/disk/part_dos.c
@@ -77,8 +77,10 @@
 	    (buffer[DOS_PART_MAGIC_OFFSET + 1] != 0xaa) ) {
 		return (-1);
 	} /* no DOS Signature at all */
-	if(strncmp((char *)&buffer[DOS_PBR_FSTYPE_OFFSET],"FAT",3)==0)
+	if (strncmp((char *)&buffer[DOS_PBR_FSTYPE_OFFSET],"FAT",3)==0 ||
+	    strncmp((char *)&buffer[DOS_PBR32_FSTYPE_OFFSET],"FAT32",5)==0) {
 		return DOS_PBR; /* is PBR */
+	}
 	return DOS_MBR;	    /* Is MBR */
 }