phy: fsl-imx8mq-usb: Clear the PCS_TX_SWING_FULL field before using it

phy: fsl-imx8mq-usb: Clear the PCS_TX_SWING_FULL field before using it

Clear the PCS_TX_SWING_FULL field mask before setting the new value
in PHY_CTRL5 register. Without clearing the mask first, the OR operation
could leave previously set bits, resulting in incorrect register
configuration.

Fixes: 63c85ad0cd81 ("phy: fsl-imx8mp-usb: add support for phy tuning")
Suggested-by: Leonid Segal <leonids@variscite.com>
Acked-by: Pierluigi Passaro <pierluigi.p@variscite.com>
Signed-off-by: Stefano Radaelli <stefano.r@variscite.com>
Reviewed-by: Xu Yang <xu.yang_2@nxp.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Reviewed-by: Fabio Estevam <festevam@gmail.com>
Reviewed-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Link: https://patch.msgid.link/20251219160912.561431-1-stefano.r@variscite.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>