ARM: OMAP: h4 must have blinky leds!!

This adds generic support for the "debug board" LEDs used by most of
TI's OMAP reference boards, and board-specific support for the H4.

It's derived from the not-as-generic stuff used by OMAP1 H2/H3/P2.
Those should be able to switch easily to this version, and clean up
some of the omap1-specific code.

In addition to H4 support, one key improvement is supporting not just
the "old" ARM debug LED API (with timer and idle LEDs, plus four that
can be handy for kernel debugging), but it also supports the "new"
generic LED API (most useful for usermode stuff IMO).  Either or both
APIs can be enabled.

Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>