arch-arm: Fix reg dependency for SVE gather microops
arch-arm: Fix reg dependency for SVE gather microops

The first microop of an SVE gather creates a copy of the
source vecreg into AA64FpUreg0. The subsequent microops
must refer to this copy as a source in order to establish
the correct register dependencies.

Change-Id: I84d8c331f9f9ebca609948a15f686a7cde67dc31
Signed-off-by: Gabor Dozsa <4c5a2daf99dab97d3a4a458d9ee9896239b35fd4@arm.com>
Reviewed-by: Giacomo Gabrielli <994b1a8ccf1e7b92fe64d091082ee5c7e191855a@arm.com>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/19172
Reviewed-by: Andreas Sandberg <c9f5686ee5bd561c93f9de79681eee75bfa7f36e@arm.com>
Maintainer: Andreas Sandberg <c9f5686ee5bd561c93f9de79681eee75bfa7f36e@arm.com>
Tested-by: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>

gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5,gem5/gem5