RISC-V: fix sifive and thead section mismatches in errata

When CONFIG_MODULES is set, __init_or_module becomes <empty>, but when
CONFIG_MODULES is not set, __init_or_module becomes __init.
In the latter case, it causes section mismatch warnings:

WARNING: modpost: vmlinux.o: section mismatch in reference: riscv_fill_cpu_mfr_info (section: .text) -> sifive_errata_patch_func (section: .init.text)
WARNING: modpost: vmlinux.o: section mismatch in reference: riscv_fill_cpu_mfr_info (section: .text) -> thead_errata_patch_func (section: .init.text)

Fixes: bb3f8948 ("RISC-V: hwprobe: Remove __init on probe_vendor_features()")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reviewed-by: Evan Green <evan@rivosinc.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20230429155247.12131-1-rdunlap@infradead.org


Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>