recovery: handle security footer before passing size to mke2fs

mke2fs doesn't take negative size as reserved size. If footer is
specified, compute fs size to be
(max partition size - reserved footer size) / block_size

Bug: 23686092
Bug: 63968011
Merged-In: Iac4e143bd26a70cfc81eb52a399d687e19b1049c
Change-Id: Iac4e143bd26a70cfc81eb52a399d687e19b1049c
(cherry picked from commit f3ccad58ddb256150858df55a5e6fe5a906c5754)