Revert "tty: serial: OMAP: ensure FIFO levels are set correctly in non-DMA mode"

This reverts commit 0a697b22252c9d7208b5fb3e9fbd124dd229f1d2 as Paul
wants to rework it.

Cc: Paul Walmsley <paul@pwsan.com>
Cc: Tomi Valkeinen <tomi.valkeinen@ti.com>
Cc: Govindraj Raja <govindraj.r@ti.com>
Cc: Kevin Hilman <khilman@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>