Revert Constant name to MIN_SECTORS_PER_ENTRY
Revert Constant name to MIN_SECTORS_PER_ENTRY

The previous commit changed the name of MIN_SECTORS_PER_ENTRY
to MIN_SECTORS_TO_CACHE, in an effort to be consistent with the
MiqHyperVDisk class from which this code is extracted.  However
the original name here is more appropriate and it will be changed
back.

rsevilla87/manageiq-gems-pending,aljesusg/manageiq-gems-pending,aljesusg/manageiq-gems-pending,rsevilla87/manageiq-gems-pending