ARM: dts: msm: Fix APQ8084 SMB1357 cdp board dts

Remove the mdm entry from the standalone APQ8084 smb1357 dts file
since this target does not have an external modem.

CRs-Fixed: 692099
Change-Id: Ieb5fda7b888a75a96de0e54b29e962df9589b46c
Signed-off-by: Hanumant Singh <hanumant@codeaurora.org>