[riscv-port] RFR: 8280423: riscv: Unnecessary i2l conversion in LIRGenerator::emit_array_address

[Feilong Jiang]

This fix is similar with JDK-8278417, which calls `generate_address` directly to generate address for array access.

All jtregs were tested on QEMU passed without new failures.

-------------

Commit messages:
 - 8280423: riscv: Unnecessary i2l conversion in LIRGenerator::emit_array_address

Changes: https://git.openjdk.java.net/riscv-port/pull/50/files
 Webrev: https://webrevs.openjdk.java.net/?repo=riscv-port&pr=50&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280423
  Stats: 18 lines in 1 file changed: 3 ins; 14 del; 1 mod
  Patch: https://git.openjdk.java.net/riscv-port/pull/50.diff
  Fetch: git fetch https://git.openjdk.java.net/riscv-port pull/50/head:pull/50

PR: https://git.openjdk.java.net/riscv-port/pull/50