OMAP4: Add ION initialization to board file

From: http://git.omapzoom.org/?p=kernel/omap.git;a=blobdiff;f=arch/arm/mach-omap2/board-44xx-tablet.c;h=b3cb3d72a6fab740fde232953e1f9ca65025788d;hp=48b775a4377b3a3b548786d6c7797d42ffdb1c97;hb=822b5fb0df4585ba72f61a4622b88d2445a90ba9;hpb=cb5823228eac29f8ebc039272b7a71a1832f7ba3 
OMAP4: Tablet: Add ION initialization to board file