libbpf: Fix syscall access arguments on riscv

libbpf: Fix syscall access arguments on riscv

[ Upstream commit 8a412c5c1cd6cc6c55e8b9b84fbb789fc395fe78 ]

Since commit 08d0ce30e0e4 ("riscv: Implement syscall wrappers"), riscv
selects ARCH_HAS_SYSCALL_WRAPPER so let's use the generic implementation
of PT_REGS_SYSCALL_REGS().

Fixes: 08d0ce30e0e4 ("riscv: Implement syscall wrappers")
Signed-off-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Sami Tolvanen <samitolvanen@google.com>
Link: https://lore.kernel.org/bpf/20231004110905.49024-2-bjorn@kernel.org
Signed-off-by: Sasha Levin <sashal@kernel.org>