USB: fsl-mph-dr-of: fix regression on mpc5121e

fsl-ehci probing fails on mpc5121e:
...
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
fsl-ehci fsl-ehci.0: Freescale On-Chip EHCI Host Controller
fsl-ehci fsl-ehci.0: new USB bus registered, assigned bus number 1
fsl-ehci fsl-ehci.0: Could not get controller version
fsl-ehci fsl-ehci.0: can't setup
fsl-ehci fsl-ehci.0: USB bus 1 deregistered
fsl-ehci fsl-ehci.0: init fsl-ehci.0 fail, -22
fsl-ehci: probe of fsl-ehci.0 failed with error -22

Fix it by returning appropriate version info for mpc5121, too.

Signed-off-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>