drm/nouveau: remove unused increment in gm200_flcn_pio_imem_wr

drm/nouveau: remove unused increment in gm200_flcn_pio_imem_wr

The 'tag' parameter is passed by value and is not actually used after
being incremented, so remove the increment.  It's the function that calls
gm200_flcn_pio_imem_wr that is supposed to (and does) increment 'tag'.

Fixes: 0e44c2170876 ("drm/nouveau/flcn: new code to load+boot simple HS FWs (VPR scrubber)")
Reviewed-by: Philipp Stanner <phasta@kernel.org>
Signed-off-by: Timur Tabi <ttabi@nvidia.com>
Link: https://lore.kernel.org/r/20250813001004.2986092-2-ttabi@nvidia.com
Signed-off-by: Danilo Krummrich <dakr@kernel.org>