defconfig: arm: Disable DEVMEM and DEVKMEM for couple of SoCs

testDevMemSane & testDevkmemSane test cases are introduced
in latest Android-6.0 version of CTS. These testcases expect
mem and kmem nodes should not be present in /dev.
So disable DEVMEM and DEVKMEM flags in msm8937_defconfig file
for msm8937 and msmgold SoCs and in msmcortex_defconifg file
for msmtitanium SoC.

Change-Id: I607e59f6fcb4a6d0d76ffb7e9a42adf8f79e76f1
Signed-off-by: Prasad Sodagudi <psodagud@codeaurora.org>