device/dram/ddr3: Fix calculation CRC16 of SPD

Fix regression with commit:
   7dc4b84 device/dram/ddr3: Calculate CRC16 of SPD unique identifier

Misplaced parenthesis causes CRC check failure, potentially
rendering some platform unbootable.

Change-Id: I9699ee2ead5b99c7f46f6f4682235aae3125cca6
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: https://review.coreboot.org/17550
Tested-by: build bot (Jenkins)
Reviewed-by: David Hendricks <dhendrix@chromium.org>

src/device/dram/ddr3.c

@@ -52,7 +52,7 @@ static u16 crc16(const u8 *ptr, int n_crc)
 	u16 crc = 0;
 
 	while (--n_crc >= 0) {
-		crc = (crc ^ (int)*ptr++) << 8;
+		crc = crc ^ ((int)*ptr++ << 8);
 		for (i = 0; i < 8; ++i)
 			if (crc & 0x8000) {
 				crc = (crc << 1) ^ 0x1021;