powerpc/pseries/vas: use default_groups in kobj_type

powerpc/pseries/vas: use default_groups in kobj_type

There are currently 2 ways to create a set of sysfs files for a
kobj_type, through the default_attrs field, and the default_groups
field.  Move the pseries vas sysfs code to use default_groups field
which has been the preferred way since aa30f47cf666 ("kobject: Add
support for default attribute groups to kobj_type") so that we can soon
get rid of the obsolete default_attrs field.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Haren Myneni <haren@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-kernel@vger.kernel.org
Link: https://lore.kernel.org/r/20220329142552.558339-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>