firmware: dmi_scan: Fix dmi_len type

According to SMBIOSv3 specification the length of DMI table can be
up to 32bits wide. So use appropriate type to avoid overflow.

It's obvious that dmi_num theoretically can be more than u16 also,
so it's can be changed to u32 or at least it's better to use int
instead of u16, but on that moment I cannot imagine dmi structure
count more than 65535 and it can require changing type of vars that
work with it. So I didn't correct it.
Acked-by: NArd Biesheuvel <ard@linaro.org>
Signed-off-by: NIvan Khoronzhuk <ivan.khoronzhuk@linaro.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NMatt Fleming <matt.fleming@intel.com>

drivers/firmware/dmi_scan.c

@@ -78,7 +78,7 @@ static const char * __init dmi_string(const struct dmi_header *dm, u8 s)
  *	We have to be cautious here. We have seen BIOSes with DMI pointers
  *	pointing to completely the wrong place for example
  */
-static void dmi_table(u8 *buf, int len, int num,
+static void dmi_table(u8 *buf, u32 len, int num,
 		      void (*decode)(const struct dmi_header *, void *),
 		      void *private_data)
 {
@@ -115,7 +115,7 @@ static void dmi_table(u8 *buf, int len, int num,
 }
 
 static phys_addr_t dmi_base;
-static u16 dmi_len;
+static u32 dmi_len;
 static u16 dmi_num;
 
 static int __init dmi_walk_early(void (*decode)(const struct dmi_header *,