riscv: Define __riscv_copy_{,vec_}{words,bytes}_unaligned() using SYM_TYPED_FUNC_START

riscv: Define __riscv_copy_{,vec_}{words,bytes}_unaligned() using SYM_TYPED_FUNC_START

After commit 67bdd7b01387 ("riscv: Split out measure_cycles() for
reuse") and commit c03ad15f7cf6 ("riscv: Reuse measure_cycles() in
check_vector_unaligned_access()"), there are CFI failure when booting
kernels with CONFIG_CFI=y:

  CFI failure at measure_cycles+0x38/0xe0 (target: __riscv_copy_words_unaligned+0x0/0x50; expected type: ...)
  CFI failure at measure_cycles+0x38/0xe0 (target: __riscv_copy_vec_words_unaligned+0x0/0x24; expected type: ...)

The __riscv_copy_*_unaligned() functions are now called indirectly but
they are not defined with SYM_TYPED_FUNC_START, which is required for
assembly functions called indirectly from C to pass CFI checking. Switch
to SYM_TYPED_FUNC_START to clear up the CFI failures.

Fixes: 67bdd7b01387 ("riscv: Split out measure_cycles() for reuse")
Fixes: c03ad15f7cf6 ("riscv: Reuse measure_cycles() in check_vector_unaligned_access()")
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Reviewed-by: Nam Cao <namcao@linutronix.de>
Link: https://patch.msgid.link/20260406-measure_cycles-cfi-failure-v1-1-03e0234ae02f@kernel.org
Signed-off-by: Paul Walmsley <pjw@kernel.org>