i2c: mediatek: Fix send master code at more than 1MHz

There are some omissions in the previous patch about replacing
I2C_MAX_FAST_MODE__FREQ with I2C_MAX_FAST_MODE_PLUS_FREQ and
need to fix it.

Fixes: b44658e7("i2c: mediatek: Send i2c master code at more than 1MHz")
Signed-off-by: Qii Wang <qii.wang@mediatek.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>