omap USB_DPLL not configured as per manual

[Roger Quadros <rogerq@ti.com>]

Hi Tero,

The USB_DPLL doesn't have recommended M/N settings as per the TRM [1]
Thus the omapconf audit fails.

Any ideas of how we can fix this up? Should we add a new clock.ops structure for
USB_DPLL to make sure that we don't violate the TRM recommended settings?
or should we just add some flags in dpll_data? We would need a new compatible id for sure.

[1] - OMAP4460_ES1.x_NDA_TRM_vP.pdf - 3.6.3.9.5 DPLL_USB Preferred Settings

panda4460> omapconf audit dpll -d usb
|-------------------------------------------------------------------------------------|
| DPLL_USB AUDIT (@OPP OPP100, sysclk=38.4MHz) | Current Setting | Expected  | STATUS |
|-------------------------------------------------------------------------------------|
| Status                                       | Locked          | Locked    | Pass   |
| Mode                                         | Lock            | Lock      | Pass   |
| Autoidle Mode                                | Auto LPST       | Auto LPST | Pass   |
| Low-Power Mode                               | Disabled        | Disabled  | Pass   |
| REGM4XEN Mode                                | Disabled        | Disabled  | Pass   |
| DCC Mode                                     | Disabled        | Disabled  | Pass   |
| M Divider                                    | 25              | 400       | FAIL   |
| N Divider                                    | 0               | 15        | FAIL   |
| Lock Frequency                               | 960.0MHz        | 960.0MHz  | Pass   |
| M2 Divider                                   | 2               | 2         | Pass   |
| CLKOUT Output Rate                           | 480.0MHz        | 480.0MHz  | Pass   |
| CLKDCOLDO Output Rate                        | 960.0MHz        | 960.0MHz  | Pass   |
|-------------------------------------------------------------------------------------|

cheers,
-roger