uboot-imx

ddr: altera: Replace ad-hoc constant with macro

The bit 22 is in fact DQS tracking enable bit (dqstrken) and there
is a macro for this bit already, so use it.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: Chin Liang See <clsee@altera.com>