MIPS64: Fix load in Generate_JSConstructStubGeneric

This patch fixes regresion introduced in CL:
https://chromium-review.googlesource.com/c/489525/

ldr instruction is unaligned load on MIPS and it is not available in
MIPS64r6 architecture.

BUG=

Review-Url: https://codereview.chromium.org/2873873005
Cr-Commit-Position: refs/heads/master@{#45257}

src/builtins/mips64/builtins-mips64.cc

@@ -587,8 +587,8 @@ void Generate_JSConstructStubGeneric(MacroAssembler* masm,
     // -----------------------------------
 
     // Restore constructor function and argument count.
-    __ ldr(a1, MemOperand(fp, ConstructFrameConstants::kConstructorOffset));
-    __ ldr(a0, MemOperand(fp, ConstructFrameConstants::kLengthOffset));
+    __ Ld(a1, MemOperand(fp, ConstructFrameConstants::kConstructorOffset));
+    __ Ld(a0, MemOperand(fp, ConstructFrameConstants::kLengthOffset));
     __ SmiUntag(a0);
 
     // Set up pointer to last argument.