lib: sbi_pmu: ensure update hpm counter before starting counting

When detecting features of PMU, the hpm counter may be written to some
value, this will cause some unexpected behavior in some cases. So ensure
the hpm counter is updated before starting the counter and the related
interrupt.

Signed-off-by: Haijiao Liu <haijiao.liu@sophgo.com>
Co-authored-by: Inochi Amaoto <inochiama@outlook.com>
Signed-off-by: Inochi Amaoto <inochiama@outlook.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Tested-by: Samuel Holland <samuel@sholland.org>