usb: dwc3: dwc3-octeon: Verify clock divider

Although valid USB clock divider will be calculated for all valid
Octeon core frequencies, make code formally correct limiting
divider not to be greater that 7 so it fits into H_CLKDIV_SEL
field.

Signed-off-by: Ladislav Michl <ladis@linux-mips.org>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://qa-reports.linaro.org/lkft/linux-next-master/build/next-20230808/testrun/18882876/suite/build/test/gcc-8-cavium_octeon_defconfig/log


Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/ZNIM7tlBNdHFzXZG@lenoch


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>