After the machine name change, the default setting for PLATFORM_FLAVOR no longer
works.
```
| core/arch/arm/plat-imx/conf.mk:211: *** Unsupported PLATFORM_FLAVOR "mx8qm-mek". Stop.
```
Set the correct name again manually with SOC override.
Signed-off-by: Tom Hochstein <tom.hochstein@nxp.com>
PLATFORM_FLAVOR_imx6ulz-14x14-evk = "mx6ulzevk"
PLATFORM_FLAVOR_mx8mm = "mx8mmevk"
PLATFORM_FLAVOR_mx8mn = "mx8mnevk"
-PLATFORM_FLAVOR_mx8qxp = "mx8qxpmek"
PLATFORM_FLAVOR_mx8mp = "mx8mpevk"
+PLATFORM_FLAVOR_mx8qm = "mx8qmmek"
+PLATFORM_FLAVOR_mx8qxp = "mx8qxpmek"
PLATFORM_FLAVOR_mx8dx = "mx8dxmek"
PLATFORM_FLAVOR_mx8dxl = "mx8dxlevk"