Revert "Revert "arm: mm: Add VM_ARM_EMPTY_MAPPING flag to mark the PMD gaps""

This reverts commit 9834b4d5207ee13536bc41f3a9d98702c0cd9c7a.
Revert "ARM: 7527/1: uaccess: explicitly check __user pointer when !CPU_USE_DOMAINS"

This reverts commit 8cc876def310b034ab0e0775a14d1a49472d7f5f.
msm: restart: Always use Samsung magic restart reason

 * If this isn't passed, the bootloader won't honor the
   values written to the bootmode in the param partition.

Change-Id: I1e6d2d47b9cc762b19a48a7edb7abaa296e9e0dc
Merge remote-tracking branch 'upstream/cm-10.1' into HEAD