diags: Do not run diagnostics on disks
diags: Do not run diagnostics on disks

Presently we are using lsvpd to get all sg devices. This list
includes disks as well. So we end up doing extra validation
for these devices. Also the present output message is not
proper.

This patch gets lists of enclosures based on sysfs. This approach
is efficient than lsvpd approach and fixes above described issue.

Output without patch:
[root@eagle3 diags]# /diag_encl
  DIAGNOSING sg1		<-- sg1 is disk, not enclosure
	Model    : CBRCA300C3ETS0
	Location : U78A5.001.WIH8464-P1-T3-B2-T0-L0

	Unable to diagnose devices of machine type/model CBRCA300C3ETS0

  ...
  ...

Output with patch:
  [root@eagle3 diags]# diag_encl
  DIAGNOSING sg2
	Model    : CBRCA300C3ETS0
	Location : U78A5.001.WIH8464-P1-T3-B6-T0-L0

	Unable to diagnose devices of machine type/model CBRCA300C3ETS0

	DIAGNOSING sg3
	Model    : VSBPD1BK
	Location : U78A5.001.WIH8464-P1-T3-B8-T0-L0

	Unable to diagnose devices of machine type/model VSBPD1BK

Signed-off-by: Vasant Hegde <a6d753843573f7bfed5075c1e875b0be8007a0ab@linux.vnet.ibm.com>
Reviewed-by: Suzuki K Poulose <2d5cd350c7a48263c670a6374c5c55bca8d1a68a@in.ibm.com>

tyreld/ppc64-diag,leitao/ppc64-diag,leitao/ppc64-diag,leitao/ppc64-diag,leitao/ppc64-diag,tyreld/ppc64-diag,tyreld/ppc64-diag,tyreld/ppc64-diag