msm: kgsl: Fix spinlock recursion in destroy pagetable

pagetable list is protected by ptlock. Few functions
while iterating over a pagetable list takes same ptlock,
kgsl_destroy_pagetable() also need same lock. This will
cause spinlock recursion if kgsl_destroy_pagetable()
called while iterating over a list. Created two versions
of same function one is with lock and other is without
lock.

CRs-Fixed: 621172
Change-Id: I61440f99022fce8629a57bb5661e2eef9613187b
Signed-off-by: Prakash Kamliya <pkamliya@codeaurora.org>