fs: befs: check silent flag before logging error

Log error only when silent flag is not set.

Fixes: dbe6460388bc ("fs/befs/linuxvfs.c: check silent flag before logging errors")
Signed-off-by: Luis de Bethencourt <luisbg@osg.samsung.com>
Acked-by: Salah Triki <salah.triki@gmail.com>