configs: imx6q_logic: Cleanup ramdiskaddr and fdtaddr

There are already definitions for ramdisk_addr_r and fdt_addr_r, so
having a duplicate copy called ramdiskaddr and fdtaddr is confusing.
This patch converts any references to ramdisk_addr_r and fdt_addr_r
and removes the duplicates.

Signed-off-by: Adam Ford <aford173@gmail.com>