vfat: Fix mkcksum argument sizes

In case a function argument is known/fixed size array in C, the argument is
still decoyed as pointer instead ( T f(U n[k]) ~= T fn(U *n) ) and therefore
calling sizeof on the function argument will result in the size of the pointer,
not the size of the array.

The VFAT code contains such a bug, this patch fixes it.

Reported-by: Aaron Williams <Aaron.Williams@cavium.com>
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Tom Rini <tom.rini@gmail.com>
Cc: Aaron Williams <Aaron.Williams@cavium.com>
Tested-by: Michal Simek <michal.simek@xilinx.com>
Reviewed-by: Joe Hershberger <joe.hershberger@ni.com>

fs/fat/fat.c

@@ -569,9 +569,9 @@ static __u8 mkcksum(const char name[8], const char ext[3])
 
 	__u8 ret = 0;
 
-	for (i = 0; i < sizeof(name); i++)
+	for (i = 0; i < 8; i++)
 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + name[i];
-	for (i = 0; i < sizeof(ext); i++)
+	for (i = 0; i < 3; i++)
 		ret = (((ret & 1) << 7) | ((ret & 0xfe) >> 1)) + ext[i];
 
 	return ret;