wic: Fix bad directory name in bootimg-efi

The original move of the mkefidisk code to the bootimg-efi plugin
resulted in a bad hdddir - fix it.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
wic: Remove fstype from mkefidisk canned wks

The bootimg-efi plugin specifies the fstype internally, so remove it
from the partition definition.

Signed-off-by: Tom Zanussi <tom.zanussi@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>