usb: gsi: Dont mask read api for dpl_ctl node

Commit ("1fc901db usb: gsi: Mask the read/write apis for
dpl_ctrl node") masked gsi_ctrl_dev_read() API for DPL
interface which results into dpl daemon not receiving any
USB cable status change notification using ZLP packet.
Hence dont mask read api for dpl_ctl node.

Change-Id: I3f283d0e0108cc36b1fa0f7a53ab52e8e02962ef
Signed-off-by: Elson Roy Serrao <eserrao@codeaurora.org>