auxdisplay: ht16k33: Use HT16K33_FB_SIZE in ht16k33_initialize()

Use the existing HT16K33_FB_SIZE definition instead of open-coding the
same calculation using an hardcoded value.
While at it, restore reverse Christmas tree variable declaration order.
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Robin van der Gracht <robin@protonic.nl>
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

drivers/auxdisplay/ht16k33.c

@@ -168,9 +168,9 @@ static void ht16k33_fb_update(struct work_struct *work)
 
 static int ht16k33_initialize(struct ht16k33_priv *priv)
 {
+	uint8_t data[HT16K33_FB_SIZE];
 	uint8_t byte;
 	int err;
-	uint8_t data[HT16K33_MATRIX_LED_MAX_COLS * 2];
 
 	/* Clear RAM (8 * 16 bits) */
 	memset(data, 0, sizeof(data));