[riscv64] Alter MaxPCRelativeCodeRangeInMB

In riscv64, pc-relatice call need meet IsInt32(offset + 0x800), so max pcrelatice code range is 4094MB.

Change-Id: Id3481483eb3131b5c08f22bde08206ee30cc25db
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3156585
Commit-Queue: Ji Qiu <qiuji@iscas.ac.cn>
Reviewed-by: Ji Qiu <qiuji@iscas.ac.cn>
Cr-Commit-Position: refs/heads/main@{#76794}

src/codegen/riscv64/constants-riscv64.h

@@ -57,7 +57,7 @@ const uint32_t kLessSignificantWordInDoublewordOffset = 4;
 namespace v8 {
 namespace internal {
 
-constexpr size_t kMaxPCRelativeCodeRangeInMB = 4096;
+constexpr size_t kMaxPCRelativeCodeRangeInMB = 4094;
 
 // -----------------------------------------------------------------------------
 // Registers and FPURegisters.