OMAP3/4: Increase console I/O buffer size

OMAP3/4: Increase console I/O buffer size

Increase the console I/O buffer size (SYS_CBSIZE) to 512 (from 256)
required especially for bootargs string, as multiple options
(e.g Video settings) are passed to the kernel through bootargs.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Signed-off-by: Sandeep Paulraj <s-paulraj@ti.com>