RFR: 8318723: RISC-V: C2 UDivL

[Hamlin Li]

Hi,
Can you review the change to add intrinsic for UDivI and UDivL?
Thanks!


## Tests

### Functionality
Run tests successfully found via `grep -nr test/jdk/ -we divideUnsigned` and `grep -nr test/hotspot/ -we divideUnsigned` 

### Performance
#### Long
** Before **

LongDivMod.testDivideUnsigned                    1024          mixed  avgt    2  19852.277          ns/op
LongDivMod.testDivideUnsigned                    1024       positive  avgt    2  29155.681          ns/op
LongDivMod.testDivideUnsigned                    1024       negative  avgt    2   6385.280          ns/op


** After **

LongDivMod.testDivideUnsigned                    1024          mixed  avgt    2  11776.806          ns/op
LongDivMod.testDivideUnsigned                    1024       positive  avgt    2  16101.940          ns/op
LongDivMod.testDivideUnsigned                    1024       negative  avgt    2   6433.223          ns/op


#### Integer
** Before **

IntegerDivMod.testDivideUnsigned                    1024          mixed  avgt    2  23498.570          ns/op
IntegerDivMod.testDivideUnsigned                    1024       positive  avgt    2  16875.614          ns/op
IntegerDivMod.testDivideUnsigned                    1024       negative  avgt    2  30310.243          ns/op


** After **

IntegerDivMod.testDivideUnsigned                    1024          mixed  avgt    2  23327.997          ns/op
IntegerDivMod.testDivideUnsigned                    1024       positive  avgt    2  16708.209          ns/op
IntegerDivMod.testDivideUnsigned                    1024       negative  avgt    2  30162.153          ns/op

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

Commit messages:
 - Modify tests to run for riscv64
 - reuse riscv_enc_divuw and corrected_idiv
 - space and comments
 - Initial commit

Changes: https://git.openjdk.org/jdk/pull/16346/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=16346&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8318723
  Stats: 74 lines in 5 files changed: 62 ins; 0 del; 12 mod
  Patch: https://git.openjdk.org/jdk/pull/16346.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16346/head:pull/16346

PR: https://git.openjdk.org/jdk/pull/16346