ARMV7: OMAP3: Add CONFIG_SYS_NAND_QUIET_TEST to Beagle and Overo configs

Future versions of these boards have options for POP memory with no NAND.
This option prevents display of error messages when no NAND is detected.

Signed-off-by: Steve Sakoman <steve@sakoman.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>