ARM: OMAP1: Move UART defines to prepare for sparse IRQ

These have been indirectly included via asm/irqs.h that
has included mach/hardware.h unless SPARSE_IRQ is specified.
Let's move them to where the other OMAP serial defines for
8250 are.

Cc: Aaro Koskinen <aaro.koskinen@iki.fi>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Tony Lindgren <tony@atomide.com>