usb: musb: dsps: remove EOI access

The EOI register is not present in the AM335x memory space according to
the TRM and thus removed.
Should any platform using the EOI register get merged then it may be
used again if the register address is not zero.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Felipe Balbi <balbi@ti.com>