OMAP: UART: drop OMAP_TAG_UART, enable all UARTs, auto-disabled on idle

OMAP tags are deprecrated so drop them.

Drop UART config data which decides which UARTs to enable during boot.
This is no longer necessary since serial core code disables clocks
after inactivity.

Background: with new UART idle code, all on-chip UARTs are idled using
a configurable inactivity timer (default 5 seconds.)  After the
inactivity timer, UART clocks are disabled automatically.

Signed-off-by: Kalle Valo <kalle.valo@iki.fi>
Signed-off-by: Kevin Hilman <khilman@deeprootsystems.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>