openrisc: Add jump label support

Supported a complete jump_label implementation based on the ARM64 and
RV64 version and add the CONFIG_JUMP_LABEL=y to the defconfig.

Testing was conducted using a dedicated test module jump-label-test,
provided in the link below. For detailed steps, please refer to the
README also at the provided link.

Link: https://github.com/ChenMiaoi/GSoC-2025-Final-Report/tree/main/tests/jump-label-test

Test Environment:
  - Hardware: QEMU emulated OR1K
  - Kernel Version: 6.17.0-rc3-dirty
  - Configs: CONFIG_MODULES=y,CONFIG_MODULE_UNLOAD=y
  - Toolchain: or1k-none-linux-musl-gcc 15.1.0

Test Results:
$ insmod jump_label_test.ko
[   32.590000] Jump label performance test module loaded
[   35.250000] Normal branch time: 1241327150 ns (124 ns per iteration)
[   35.250000] Jump label (false) time: 706422700 ns (70 ns per iteration)
[   35.250000] Jump label (true) time: 708913450 ns (70 ns per iteration)
$ rmmod jump_label_test.ko
[   72.210000] Jump label test module unloaded

The results show approximately 43% improvement in branch performance
when using jump labels compared to traditional branches.

Link: https://lore.kernel.org/openrisc/aLsZ9S3X0OpKy1RM@antec/T/#u


Signed-off-by: chenmiao <chenmiao.ku@gmail.com>
Signed-off-by: Stafford Horne <shorne@gmail.com>