RISC-V: Fix counter restart during overflow for RV32

Pass the upper half of the initial value of the counter correctly
for RV32.

Fixes: 4905ec2f

 ("RISC-V: Add sscofpmf extension support")
Signed-off-by: Atish Patra <atishp@rivosinc.com>
Reviewed-by: Guo Ren <guoren@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20220711174632.4186047-2-atishp@rivosinc.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>