Make fsck_y_enable default to passing pass -R to fsck_ffs(8) in addition
to -y. To me, fsck_y_enable means "try as hard as possible", and without
-R, it... well, doesn't.

Reviewed by: mckusick
Obtained from: CheriBSD
MFC after: 2 weeks
Sponsored by: DARPA, AFRL
Differential Revision: https://reviews.freebsd.org/D11490