i2c: mt7621: reword according to newest specification

i2c: mt7621: reword according to newest specification

Change the wording of this driver wrt. the newest I2C v7 and SMBus 3.2
specifications and replace "master/slave" with more appropriate terms.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Andi Shyti <andi.shyti@kernel.org>
Signed-off-by: Andi Shyti <andi.shyti@kernel.org>