ARM: OMAP3: beagle-board: Use the omap_hwmod_name_get_dev API

Replace the multiple omap2_get_XXX_device APIs with the new
omap_hwmod_name_get_dev that uses the hwmod name to get the proper
device.

Signed-off-by: Benoit Cousson <b-cousson@ti.com>
Cc: Nishanth Menon <nm@ti.com>
Signed-off-by: Kevin Hilman <khilman@ti.com>