RISC-V: Do not allocate memblock while iterating reserved memblocks

RISC-V: Do not allocate memblock while iterating reserved memblocks

Currently, resource tree allocates memory blocks while iterating on the
list. It leads to following kernel warning because memblock allocation
also invokes memory block reservation API.

[    0.000000] ------------[ cut here ]------------
[    0.000000] WARNING: CPU: 0 PID: 0 at kernel/resource.c:795
__insert_resource+0x8e/0xd0
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted
5.10.0-00022-ge20097fb37e2-dirty #549
[    0.000000] epc: c00125c2 ra : c001262c sp : c1c01f50
[    0.000000]  gp : c1d456e0 tp : c1c0a980 t0 : ffffcf20
[    0.000000]  t1 : 00000000 t2 : 00000000 s0 : c1c01f60
[    0.000000]  s1 : ffffcf00 a0 : ffffff00 a1 : c1c0c0c4
[    0.000000]  a2 : 80c12b15 a3 : 80402000 a4 : 80402000
[    0.000000]  a5 : c1c0c0c4 a6 : 80c12b15 a7 : f5faf600
[    0.000000]  s2 : c1c0c0c4 s3 : c1c0e000 s4 : c1009a80
[    0.000000]  s5 : c1c0c000 s6 : c1d48000 s7 : c1613b4c
[    0.000000]  s8 : 00000fff s9 : 80000200 s10: c1613b40
[    0.000000]  s11: 00000000 t3 : c1d4a000 t4 : ffffffff

This is also unnecessary as we can pre-compute the total memblocks required
for each memory region and allocate it before the loop. It save precious
boot time not going through memblock allocation code every time.

Fixes: 545c1cf7974b ("RISC-V: Add kernel image sections to the resource tree")
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Signed-off-by: Palmer Dabbelt <palmerdabbelt@google.com>