perf: RISCV: Fix panic on pmu overflow handler

perf: RISCV: Fix panic on pmu overflow handler

(1 << idx) of int is not desired when setting bits in unsigned long
overflowed_ctrs, use BIT() instead. This panic happens when running
'perf record -e branches' on sophgo sg2042.

[  273.311852] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000098
[  273.320851] Oops [#1]
[  273.323179] Modules linked in:
[  273.326303] CPU: 0 PID: 1475 Comm: perf Not tainted 6.6.0-rc3+ #9
[  273.332521] Hardware name: Sophgo Mango (DT)
[  273.336878] epc : riscv_pmu_ctr_get_width_mask+0x8/0x62
[  273.342291]  ra : pmu_sbi_ovf_handler+0x2e0/0x34e
[  273.347091] epc : ffffffff80aecd98 ra : ffffffff80aee056 sp : fffffff6e36928b0
[  273.354454]  gp : ffffffff821f82d0 tp : ffffffd90c353200 t0 : 0000002ade4f9978
[  273.361815]  t1 : 0000000000504d55 t2 : ffffffff8016cd8c s0 : fffffff6e3692a70
[  273.369180]  s1 : 0000000000000020 a0 : 0000000000000000 a1 : 00001a8e81800000
[  273.376540]  a2 : 0000003c00070198 a3 : 0000003c00db75a4 a4 : 0000000000000015
[  273.383901]  a5 : ffffffd7ff8804b0 a6 : 0000000000000015 a7 : 000000000000002a
[  273.391327]  s2 : 000000000000ffff s3 : 0000000000000000 s4 : ffffffd7ff8803b0
[  273.398773]  s5 : 0000000000504d55 s6 : ffffffd905069800 s7 : ffffffff821fe210
[  273.406139]  s8 : 000000007fffffff s9 : ffffffd7ff8803b0 s10: ffffffd903f29098
[  273.413660]  s11: 0000000080000000 t3 : 0000000000000003 t4 : ffffffff8017a0ca
[  273.421022]  t5 : ffffffff8023cfc2 t6 : ffffffd9040780e8
[  273.426437] status: 0000000200000100 badaddr: 0000000000000098 cause: 000000000000000d
[  273.434512] [<ffffffff80aecd98>] riscv_pmu_ctr_get_width_mask+0x8/0x62
[  273.441169] [<ffffffff80076bd8>] handle_percpu_devid_irq+0x98/0x1ee
[  273.447562] [<ffffffff80071158>] generic_handle_domain_irq+0x28/0x36
[  273.454151] [<ffffffff8047a99a>] riscv_intc_irq+0x36/0x4e
[  273.459659] [<ffffffff80c944de>] handle_riscv_irq+0x4a/0x74
[  273.465442] [<ffffffff80c94c48>] do_irq+0x62/0x92
[  273.470360] Code: 0420 60a2 6402 5529 0141 8082 0013 0000 0013 0000 (6d5c) b783
[  273.477921] ---[ end trace 0000000000000000 ]---
[  273.482630] Kernel panic - not syncing: Fatal exception in interrupt

Reviewed-by: Alexandre Ghiti <alexghiti@rivosinc.com>
Reviewed-by: Atish Patra <atishp@rivosinc.com>
Signed-off-by: Fei Wu <fei2.wu@intel.com>
Link: https://lore.kernel.org/r/20240228115425.2613856-1-fei2.wu@intel.com
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>