man: modify mkfs.f2fs man page
man: modify mkfs.f2fs man page

This patch adds missing [sectors] option in mkfs.f2fs, and removes
meaningless version.

Change-Id: Ib8726f8cb5ea7b22bc0517003e66fcf5ae74ebbf
Signed-off-by: Jaegeuk Kim <71255387a32c360dfbe6dfb7aaeb123bf1dc8cb6@kernel.org>

TeamTwisted/android_external_f2fs-tools,TeamTwisted/android_external_f2fs-tools