OMAP3: Add SPL support to Beagleboard

This introduces 200MHz Micron parts timing information based on x-loader
to <asm/arch-omap3/mem.h> and Numonyx MCFG calculation.  The memory init
logic is also based on what x-loader does in these cases.  Note that
while previously u-boot would be flashed in with SW ECC in this case it
now must be flashed with HW ECC.  We also change CONFIG_SYS_TEXT_BASE to
0x80100000.

Cc: Dirk Behme <dirk.behme@gmail.com>
Beagleboard rev C5, xM rev A:
Tested-by: Tom Rini <trini@ti.com>
Beagleboard xM rev C:
Tested-by: Matt Ranostay <mranostay@gmail.com>
Beagleboard rev B7, C2, xM rev B:
Tested-by: Matt Porter <mporter@ti.com>
Signed-off-by: Tom Rini <trini@ti.com>