omap3: beagle: re-enable EFI support after the following commit removed it by mistake:

commit d233ccb1
  ARM: omap3: beagle: Enable DM_SERIAL, update distro usage and NAND layout

Signed-off-by: Guillaume GARDET <guillaume.gardet@free.fr>
Cc: Derald D. Woods <woods.technical@gmail.com>
Cc: Tom Rini <trini@konsulko.com>