sh: Fix split ptlock for user mappings in __do_page_fault().
sh: Fix split ptlock for user mappings in __do_page_fault().

There was a bug that got introduced when the split ptlock changes
went in where mm could be unintialized for user mappings, this
fixes it up..

Signed-off-by: Paul Mundt <38b52dbb5f0b63d149982b6c5de788ec93a89032@linux-sh.org>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas