MAINTAINERS: adjust file entry after renaming rzv2h-gbeth dtb

MAINTAINERS: adjust file entry after renaming rzv2h-gbeth dtb

Commit d53320aeef18 ("dt-bindings: net: Rename
renesas,r9a09g057-gbeth.yaml") renames the net devicetree binding
renesas,r9a09g057-gbeth.yaml to renesas,rzv2h-gbeth.yaml, but misses to
adjust the file entry in the RENESAS RZ/V2H(P) DWMAC GBETH GLUE LAYER
DRIVER section in MAINTAINERS.

Adjust the file entry after this file renaming.

Signed-off-by: Lukas Bulwahn <lukas.bulwahn@redhat.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://patch.msgid.link/20250627134453.51780-1-lukas.bulwahn@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>