usb: dwc2: enable FS/LS PHY clock select on STM32MP15 FS OTG

When the core is in FS host mode, using the FS transceiver, and a Low-Speed
device is connected, transceiver clock is 6Mhz.
So, to support Low-Speed devices, enable support of FS/LS Low Power mode,
so that the PHY supplies a 6 MHz clock during Low-Speed mode.
Acked-by: Minas Harutyunyan <Minas.Harutyunyan@synopsys.com>
Signed-off-by: Amelie Delaunay <amelie.delaunay@foss.st.com>
Link: https://lore.kernel.org/r/20210105094855.30763-3-amelie.delaunay@foss.st.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/dwc2/params.c

@@ -179,6 +179,8 @@ static void dwc2_set_stm32mp15_fsotg_params(struct dwc2_hsotg *hsotg)
 	p->activate_stm_id_vb_detection = true;
 	p->ahbcfg = GAHBCFG_HBSTLEN_INCR16 << GAHBCFG_HBSTLEN_SHIFT;
 	p->power_down = DWC2_POWER_DOWN_PARAM_NONE;
+	p->host_support_fs_ls_low_power = true;
+	p->host_ls_low_power_phy_clk = true;
 }
 
 static void dwc2_set_stm32mp15_hsotg_params(struct dwc2_hsotg *hsotg)