musb-new: am35x backend driver

Backend driver for MUSB OTG controllers found on TI AM35x.

It seems that on AM35X interrupt status registers can be updated
_before_ core registers. As we don't use true interrupts in U-Boot
and poll interrupt status registers instead this can result in
interrupt handler being called with non-updated core registers.
This confuses the code and result in hanged transfers.
Add a small delay in am35x_interrupt as a workaround.

Signed-off-by: Ilya Yanok <ilya.yanok@cogentembedded.com>
diff --git a/drivers/usb/musb-new/Makefile b/drivers/usb/musb-new/Makefile
index a753423..23fc735 100644
--- a/drivers/usb/musb-new/Makefile
+++ b/drivers/usb/musb-new/Makefile
@@ -10,6 +10,7 @@
 COBJS-$(CONFIG_MUSB_GADGET) += musb_uboot.o
 COBJS-$(CONFIG_MUSB_HOST) += musb_host.o musb_core.o musb_uboot.o
 COBJS-$(CONFIG_USB_MUSB_DSPS) += musb_dsps.o
+COBJS-$(CONFIG_USB_MUSB_AM35X) += am35x.o
 
 CFLAGS_NO_WARN := $(call cc-option,-Wno-unused-variable) \
 			$(call cc-option,-Wno-unused-but-set-variable) \