SERIAL: omap: simplify (2)

Simplify:
	- set ECB
	...
	- LCR mode A
	- clear TCRTLR
	- LCR mode B
	- clear ECB
	- set ECB and update other bits
	- LCR mode A
	- update XONANY

to:
	- set ECB
	...
	- LCR mode B
	- set ECB and update other bits
	- LCR mode A
	- update XONANY and clear TCRTLR

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>