IVGCVSW-6255 Investigate and fix running mobilebert with the TfLiteDelegate (CpuRef)
IVGCVSW-6255 Investigate and fix running mobilebert with the TfLiteDelegate (CpuRef)

 * Fixed bug occuring in Ref Gather Workload.

Signed-off-by: Cathal Corbett <698efcb37030a7415e79e4cf379eb09f757d0834@arm.com>
Change-Id: I3ee79f475fd9909bfbd4afb58f698439f26d6d65

ARM-software/armnn,ARM-software/armnn,ARM-software/armnn