gpu: nvgpu: Fix several issues with the buddy allocator

The issues are:

1. Non-fixed allocs must take into account explicit PTE size
   requests. Previously the PTE size was determines from the
   allocation size which was incorect. To do this, the PTE size
   is now plumbed through all GPU VA allocations. This is what
   the new alloc_pte() op does.

2. Fix buddy PTE size assignment. This changes a '<=' into a
   '<' in the buddy allocation logic. Effectively this is now
   leaving the PTE size for buddy blocks equal to the PDE block
   size as 'ANY'.

   This prevents a buddy block of PDE size which has yet to be
   allocated from having a specific PDE size. Without this its
   possible to do a fixed alloc that fails unexpectedly due to
   mismatching PDE sizes.

   Consider two PDE block sized fixed allocs that are contained
   in one buddy twice the size of a PDE block. Let's call these
   fixed allocs S and B (small and big). Let's assume that two
   fixed allocs are done, each targeting S and B, in that order.
   With the current logic the first alloc, when we create the
   two buddies S and B, causes both S and B to have a PTE size of
   SMALL. Now when the second alloc happens we attempt to find
   a buddy B with a PTE size of either BIG or ANY. But we cannot
   becasue B already has size SMALL. This casues us to appear
   like we have a conflicting fixed alloc despite this not being
   the case.

3. Misc cleanups & bug fixes:
   - Clean up some MISRA issues
   - Delete an extraneous unlock that could have caused a
     deadlock.

Bug 200105199

Change-Id: Ib5447ec6705a5a289ac0cf3d5e90c79b5d67582d
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: https://git-master.nvidia.com/r/1768582
Reviewed-by: mobile promotions <svcmobile_promotions@nvidia.com>
Tested-by: mobile promotions <svcmobile_promotions@nvidia.com>

drivers/gpu/nvgpu/common/mm/nvgpu_allocator.c

@@ -77,6 +77,11 @@ u64 nvgpu_alloc(struct nvgpu_allocator *a, u64 len)
 	return a->ops->alloc(a, len);
 }
 
+u64 nvgpu_alloc_pte(struct nvgpu_allocator *a, u64 len, u32 page_size)
+{
+	return a->ops->alloc_pte(a, len, page_size);
+}
+
 void nvgpu_free(struct nvgpu_allocator *a, u64 addr)
 {
 	a->ops->free(a, addr);