Replace vf_mask type with unsigned long to avoid a stack-out-of-bound.

This is to fix the following warning reported by KASAN the first time
adf_msix_isr_ae() gets called.

    [  692.091987] BUG: KASAN: stack-out-of-bounds in find_first_bit+0x28/0x50
    [  692.092017] Read of size 8 at addr ffff88afdf789e60 by task swapper/32/0
    [  692.092076] Call Trace:
    [  692.092089]  <IRQ>
    [  692.092101]  dump_stack+0x9c/0xcf
    [  692.092132]  print_address_description.constprop.0+0x18/0x130
    [  692.092164]  ? find_first_bit+0x28/0x50
    [  692.092185]  kasan_report.cold+0x7f/0x111
    [  692.092213]  ? static_obj+0x10/0x80
    [  692.092234]  ? find_first_bit+0x28/0x50
    [  692.092262]  find_first_bit+0x28/0x50
    [  692.092288]  adf_msix_isr_ae+0x16e/0x230 [intel_qat]

Fixes: ed8ccaef ("crypto: qat - Add support for SRIOV")
Signed-off-by: Giovanni Cabiddu <giovanni.cabiddu@intel.com>
Reviewed-by: Marco Chiappero <marco.chiappero@intel.com>
Reviewed-by: Fiona Trahe <fiona.trahe@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>