arm, am33xx: move uart soft reset code to common place

arm, am33xx: move uart soft reset code to common place

move uart soft reset code to common place and call
this function from board code, instead of copy and paste
this code for every board.

Signed-off-by: Heiko Schocher <[email protected]>
Cc: Matt Porter <[email protected]>
Cc: Lars Poeschel <[email protected]>
Cc: Tom Rini <[email protected]>
Cc: Enric Balletbo i Serra <[email protected]>
Acked-by: Tom Rini <[email protected]>
[trini: Fix igep0033 build, remove 'regval' on pcm051]
Signed-off-by: Tom Rini <[email protected]>