rockchip: allow loading larger kernels

Recent versions of the Linux kernel with many options enabled have
grown large enough to overwrite the beginning of the initrd. For
example, the kernel I use on my Rock64 and RockPro64 is 34.1 MiB,
while only 31.5 MiB are available between kernel_addr_r and
ramdisk_addr_r.

This patch moves ramdisk_addr_r up by 32 MiB on the RK3328 and RK3399,
allowing for much larger kernels.

Signed-off-by: Ben Wolsieffer <benwolsieffer@gmail.com>
Reviewed-by: Kever Yang <kever.yang@rock-chips.com>