mips: octeon: bootoctlinux: Use gd->ram_size instead of ram_get_info()

Using ram_get_info() is complicated and does not work after relocation.
Now that gd->ram_size holds the full RAM size, let's use it instead and
remove the ram_get_size logic completely.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Aaron Williams <awilliams@marvell.com>
Cc: Chandrakala Chavva <cchavva@marvell.com>
Cc: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>