radeonsi/gfx11: make flat_scratch changes for compute

radeonsi/gfx11: make flat_scratch changes for compute

make flat_scratch gen11 changes for compute

v5: optimize the code for size (Pierre-Eric)
v4: remove type cast from 64bit to 32bit (Marek Olšák)
    use radeon_set_sh_reg_seq (Marek Olšák)
    combine RSRC and scratch reg write packets (Marek Olšák)
v3: fix coding guidelines (Marek Olšák)
v2: do not skip si_resource_reference() call (Marek Olšák)

Signed-off-by: Yogesh mohan marimuthu <yogesh.mohanmarimuthu@amd.com>
Acked-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/16328>