mmc: core: remove duplicate code in mmc_rescan

If the card is removed, the wakelock has to be held for
an extended period of time to enable the user-space to
respond. The code to extend the wakelock has been
duplicated. This patch removes this duplicate code.

CRs-fixed: 684724
Change-Id: I96e4e9dec46ada7853724c36f0c2c6329f696e5d
Signed-off-by: Asutosh Das <asutoshd@codeaurora.org>