Revert "block: Expose IOCTL to get partition start sector number"

This reverts commit e959c1ce.
Sector information is identified by other means so this change
is not needed.

Change-Id: Ib9cd450085b22468853b5a4955f8760d67af51b1
Signed-off-by: AnilKumar Chimata <anilc@codeaurora.org>