ARM: dts: sti: Add fixed clock for ehci and ohci nodes in stih410-b2260.dtsi

ARM: dts: sti: Add fixed clock for ehci and ohci nodes in stih410-b2260.dtsi

On STi platforms, all clocks are enabled by BOOTROM, so CONFIG_CLK is
not set as no clock driver for STI exists.

As ehci-generic and ohci-generic drivers are used on platforms where
CONFIG_CLK is set, clk_get_bulk() returns-ENOSYS in case of
stih410-b2260.
To avoid this error, add fixed clocks for ehci and ohci nodes for
stih410-b2260 to fix the following errors:

Bus usb@9a03c00: ohci_generic usb@9a03c00: Failed to get clocks (ret=-19)
Port not available.
Bus usb@9a03e00: ehci_generic usb@9a03e00: Failed to get clocks (ret=-19)
Port not available.
Bus usb@9a83c00: ohci_generic usb@9a83c00: Failed to get clocks (ret=-19)
Port not available.
Bus usb@9a83e00: ehci_generic usb@9a83e00: Failed to get clocks (ret=-19)
Port not available.
scanning bus dwc3@9900000 for devices... 1 USB Device(s) found
       scanning usb for storage devices... 0 Storage Device(s) found

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
Cc: Marek Vasut <marex@denx.de>
Reviewed-by: Patrick Delaunay <patrick.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20250130163547.512990-2-patrice.chotard@foss.st.com
Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>