phy: freescale: phy-fsl-imx8-mipi-dphy: Fix alias name to use dashes

Devicetree spec lists only dashes as valid characters for alias names.
Table 3.2: Valid characters for alias names, Devicee Specification,
Release v0.4

Signed-off-by: Alexander Stein <alexander.stein@ew.tq-group.com>
Fixes: 3fbae284

 ("phy: freescale: phy-fsl-imx8-mipi-dphy: Add i.MX8qxp LVDS PHY mode support")
Link: https://lore.kernel.org/r/20240110093343.468810-1-alexander.stein@ew.tq-group.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>