common: cleanup _require_xfs_io_command

common: cleanup _require_xfs_io_command

We don't need to check specific flags at the end of this function
if we have checked them before. e.g, generic/071 and generic/422
are marked as notrun unexpectedly because xfs_io doesn't support
long-format help for falloc before xfsprogs v4.9.  Actually, xfs_io
has supported falloc, so these case should not be marked as notrun.

[eguan: declare local vars as local, rename param_check to
param_checked]

Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com>
Reviewed-by: Eryu Guan <eguan@redhat.com>
Signed-off-by: Eryu Guan <eguan@redhat.com>