omap: timer: add ti,am654-timer compatibility

The TI AM654 timer is compatible with the omap-timer implementation,
so add it to the compatible id list.

Signed-off-by: Sjoerd Simons <sjoerd@collabora.com>
Reviewed-by: Roger Quadros <rogerq@kernel.org>
Reviewed-by: Tom Rini <trini@konsulko.com>
Tested-by: Maxime Ripard <mripard@kernel.org>
Tested-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Cc: Francesco Dolcini <francesco@dolcini.it>
Cc: Wadim Egorov <w.egorov@phytec.de>
Signed-off-by: Nishanth Menon <nm@ti.com>