Convert lvm_mirrors to int

When the location_info is parsed and `lvm_mirrors` extracted, it is not
being converted to int. This causes some boolean checks to return True
even when there are not mirrors enabled because of the u'0'.

Closes-bug: #1258133
(cherry picked from commit 1dff30492f0ce1df3ef01ccc21353248a7207709)

Change-Id: I67c463d9f139fe326bbcab4d193c45459129b514
Merge "Convert lvm_mirrors to int" into stable/havana