Platform/96Boards/96BoardsI2cDxe: rewrite DEPEX expression for legibility

Operator precedence is funny in DEPEX expressions, so let's add some
parentheses to make it self explanatory. The resulting truth value
is the same.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
Reviewed-by: Leif Lindholm <leif@nuviainc.com>