Changed value of kGap constexpr from 32 to 128. Old value caused debugger/debug/debug-scopes test to fail

TEST=debugger/debug/debug-scopes

Bug: 
Change-Id: Ib805b84dce342b317b6cace3196fd1a9690e9d7a
Reviewed-on: https://chromium-review.googlesource.com/549928Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Commit-Queue: Ivica Bogosavljevic <ivica.bogosavljevic@imgtec.com>
Cr-Commit-Position: refs/heads/master@{#46273}