usb: gadget: s3c-hsotg: fix s3c_hsotg_write_fifo function for dedicated fifo mode

In s3c_hsotg_write_fifo function PTxFEmp/NPTxFEmp interrupts are enabled
only in shared-fifo mode. In dedicated-fifo mode they should not be used
(when enabled then cause interrupt storm).

Signed-off-by: Robert Baldyga <r.baldyga@samsung.com>
Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>