Adds a deploy step ``clean_uefi_nvram`` to remove unrequired extra UEFI
NVRAM boot entries. By default any entry matching ``HD`` as the root
device, or with a ``shim`` or ``grub`` efi file in the path will be
deleted, ensuring that disk based boot entries are removed before the
new entry is created for the written image. The ``match_patterns``
parameter allows a list of regular expressions to be passed, where a
case insensitive search in the device path will result in that entry
being deleted.
Closes-Bug: #2041901
Change-Id: I3559dc800fcdfb0322286eba30ce47041419b0c6