RandomX: optimized loading from scratchpad

Prefetches scratchpad data as soon as possible to calculate data address for the next load.

Up to ~1.4% speedup on Ryzen 7 3700X @ 4.1 GHz, RAM 3200 MHz 14-14-14-28 with optimized sub-timings:
Variant|Before H/S|After H/S
-------|----------|---------
rx/0|8663|8777
rx/wow|9867|10009
rx/loki|8652|8731

src/crypto/randomx/asm/program_loop_load.inc

@@ -1,5 +1,3 @@
-	mov rdx, rax
-	and eax, RANDOMX_SCRATCHPAD_MASK
 	lea rcx, [rsi+rax]
 	push rcx
 	xor r8,  qword ptr [rcx+0]
@@ -10,8 +8,6 @@
 	xor r13, qword ptr [rcx+40]
 	xor r14, qword ptr [rcx+48]
 	xor r15, qword ptr [rcx+56]
-	ror rdx, 32
-	and edx, RANDOMX_SCRATCHPAD_MASK
 	lea rcx, [rsi+rdx]
 	push rcx
 	cvtdq2pd xmm0, qword ptr [rcx+0]

src/crypto/randomx/asm/program_loop_store.inc

@@ -1,4 +1,3 @@
-	xor eax, eax
 	pop rcx
 	mov qword ptr [rcx+0], r8
 	mov qword ptr [rcx+8], r9