defconfig: arm64: msm: Enable free pages and kernel text read only

Enable the defconfig to mark the free pages and the kernel text pages
read only. Enable the debug config CONFIG_ARM64_PTDUMP to allow
dumping the page tables from userspace.

Change-Id: I2c9c9ecf161946769e4748e02b1fac0ced1a140c
Signed-off-by: Rohit Vaswani <rvaswani@codeaurora.org>