gpu: nvgpu: Check for split_order > max_order

gpu: nvgpu: Check for split_order > max_order

When choosing an order of buddy to start splitting from (happens when
no buddies of the requested alloc order exist) don't sit in the while
loop past max_order. This makes no sense and hangs the system.

Bug 1647902

Change-Id: I6900597d24944d3170bc76cd75f33794b07707d1
Signed-off-by: Alex Waterman <alexw@nvidia.com>
Reviewed-on: http://git-master/r/755737
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Terje Bergstrom <tbergstrom@nvidia.com>