defconfig: fsm9900: Re-enable the DEVMEM kernel config

Re-enable the support of memory device driver in order to access the
SCLTE memory region.

Change-Id: I1ad9a15278da859f9ce1bad0b43542e2f71c3bb5
Acked-by: Kaushik Sikdar <ksikdar@qti.qualcomm.com>
Signed-off-by: Venkatesh Yadav Abbarapu <quicvenkat@codeaurora.org>