vmware: fix potential NPE when memory hotplug capability is checked

[yadvr]

This fixes potential NPE case when memory hotpluggability is checked
based on the guest OS descriptor.

Fixes #3230 NPE case.

Types of changes

• Breaking change (fix or feature that would cause existing functionality to change)
• New feature (non-breaking change which adds functionality)
• Bug fix (non-breaking change which fixes an issue)
• Enhancement (improves an existing feature and functionality)
• Cleanup (Code refactoring and cleanup, that may add test cases)

[yadvr]

@blueorangutan package

[blueorangutan]

@rhtyd a Jenkins job has been kicked to build packages. I'll keep you posted as I make progress.

[blueorangutan]

Packaging result: ✔centos6 ✔centos7 ✔debian. JID-2808

[yadvr]

@blueorangutan test centos7 vmware-65u2

[blueorangutan]

@rhtyd a Trillian-Jenkins test job (centos7 mgmt + vmware-65u2) has been kicked to run smoke tests

[blueorangutan]

Trillian test result (tid-3606)
Environment: vmware-65u2 (x2), Advanced Networking with Mgmt server 7
Total time taken: 37738 seconds
Marvin logs: https://github.com/blueorangutan/acs-prs/releases/download/trillian/pr3362-t3606-vmware-65u2.zip
Intermittent failure detected: /marvin/tests/smoke/test_deploy_vm_root_resize.py
Intermittent failure detected: /marvin/tests/smoke/test_public_ip_range.py
Intermittent failure detected: /marvin/tests/smoke/test_templates.py
Intermittent failure detected: /marvin/tests/smoke/test_usage.py
Intermittent failure detected: /marvin/tests/smoke/test_volumes.py
Smoke tests completed. 65 look OK, 3 have error(s)
Only failed tests results shown below:

Test	Result	Time (s)	Test File
test_04_extract_template	Failure	144.90	test_templates.py
ContextSuite context=TestISOUsage>:setup	Error	0.00	test_usage.py
test_06_download_detached_volume	Failure	172.69	test_volumes.py

[yadvr]

Test lgtm, the failures were env related.

[nvazquez]

LGTM. Thanks @rhtyd

[shwstppr]

LGTM