riscv: Separate memory init from paging init

[ Upstream commit cbd34f4b ]

Currently, we perform some memory init functions in paging init. But,
that will be an issue for NUMA support where DT needs to be flattened
before numa initialization and memblock_present can only be called
after numa initialization.

Move memory initialization related functions to a separate function.

Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Greentime Hu <greentime.hu@sifive.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Reviewed-by: Palmer Dabbelt <palmerdabbelt@google.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>
Stable-dep-of: 50e63dd8 ("riscv: fix reserved memory setup")
Signed-off-by: Sasha Levin <sashal@kernel.org>