RFR: 8295270: RISC-V: Clean up and refactoring for assembler functions

[Fei Yang]

Witnessed that some high-level assember functions are placed in file assembler_riscv.hpp/cpp,
such as 'movptr', 'li' and so on. These are macro-assembler functions which should be placed
in macroAssembler_riscv.hpp/cpp. Meanwhile, we should also move load & store memory and
control assembler functions from addresses in 'address'/'Address' form.

Testing: Tier1 hotspot on HiFive Unmatched board {fastdebug, release}.

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Commit messages:
 - Fix trailing whitespace
 - 8295270: RISC-V: Clean up and refactoring for assembler functions

Changes: https://git.openjdk.org/jdk/pull/10697/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=10697&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8295270
  Stats: 1344 lines in 11 files changed: 637 ins; 601 del; 106 mod
  Patch: https://git.openjdk.org/jdk/pull/10697.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/10697/head:pull/10697

PR: https://git.openjdk.org/jdk/pull/10697