It is the configuration data that should go into the register,
not the register mask, just like the surrounding code does it.
Fix this typo.

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