net: phy: mediatek-ge-soc: Shrink line wrapping to 80 characters

This patch shrinks line wrapping to 80 chars. Also, in
tx_amp_fill_result(), use FIELD_PREP() to prettify code.

Signed-off-by: SkyLake.Huang <skylake.huang@mediatek.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Andrew Lunn <andrew@lunn.ch>