imx8ulp: Remove freescale name from CPU revision

Remove the freescale vendor name from CPU revision print to align
with other i.MX platforms

Reviewed-by: Peng Fan <peng.fan@nxp.com>
Signed-off-by: Ye Li <ye.li@nxp.com>
Signed-off-by: Peng Fan <peng.fan@nxp.com>