omap3_beagle: xM A/B validate new dtb exits in file system

Fall back to previous dtb used when omap3-beagle-xm-ab.dtb doesn't exist in file system

Signed-off-by: Robert Nelson <robertcnelson@gmail.com>
CC: Tom Rini <trini@ti.com>
CC: Nishanth Menon <nm@ti.com>
Acked-by: Tom Rini <trini@ti.com>
1 file changed