ARM: nxp_imx: rt10xx: rename nxp_rt.dtsi to nxp_rt10xx.dtsi

This device-tree file is only used by rt10xx dtsi files, as rt11xx (and
other families as well) have their own root SoC specific dtsi file.

Rename nxp_rt.dtsi to nxp_rt10xx.dtsi for consistency across families.

Signed-off-by: Marcin Niestroj <m.niestroj@emb.dev>