RISC-V: KVM: No need to exit to the user space if perf event failed

RISC-V: KVM: No need to exit to the user space if perf event failed

Currently, we return a linux error code if creating a perf event failed
in kvm. That shouldn't be necessary as guest can continue to operate
without perf profiling or profiling with firmware counters.

Return appropriate SBI error code to indicate that PMU configuration
failed. An error message in kvm already describes the reason for failure.

Fixes: 0cb74b65d2e5 ("RISC-V: KVM: Implement perf support without sampling")
Reviewed-by: Anup Patel <anup@brainfault.org>
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Link: https://lore.kernel.org/r/20240420151741.962500-13-atishp@rivosinc.com
Signed-off-by: Anup Patel <anup@brainfault.org>