mmc: Use byte array for multipliers

We don't need an int since no value is over 80. This saves a small amount of
SPL space (about 44 bytes).

Signed-off-by: Simon Glass <sjg@chromium.org>

drivers/mmc/mmc.c

@@ -984,7 +984,7 @@ static const int fbase[] = {
 /* Multiplier values for TRAN_SPEED.  Multiplied by 10 to be nice
  * to platforms without floating point.
  */
-static const int multipliers[] = {
+static const u8 multipliers[] = {
 	0,	/* reserved */
 	10,
 	12,